The following has been copied from http://www2.portage.net/~bjornc/mklinux/7600setup.html 
This HOWTO is based on material posted to the mklinux-misc mailing list by
David A. Gatwood. It has been edited for presentation. 
-----
It's interesting: I suggested both of these in my discussions of the 
problem with Michael Burg a few days ago. :-) I have heard from two 
people, both with different methods, both of which have systems working, 
which are otherwise technically the same as mine. Note that neither 
solves the fact that there's a bug in the program. They only get around 
the problem, and since they do require opening up the computer (pretty 
easy, really), they're not an ideal solution, but they do apparently 
solve the problem.
Two ways:
A.      Reassign the SCSI ID -- I've tried this. It works.
B.      Disconnect the internal drives from the internal bus and connect
them to the "internal/external" bus. (There's a connection on the 
motherboard for both busses, as I understand it, although I haven't 
figured out how to get that deeply into the machine to reach them...) 
The first requires little effort, but will require you to find a jumper. 
If you have a hard drive with a fixed assignment (i.e. not the wheel or 
push-button type assignment) of SCSI IDs, you could steal one from it. 
If not, you might try a local radio shack.
Since I haven't figured out how to do the second method, I won't even 
attempt to write a procedure.
Now, I have to say this, for legal reasons. 
NOTE THAT THIS PROCEDURE IS NOT IN ANY WAY ENDORSED OR RECOMMENDED BY 
ME OR THE MKLINUX TEAM. IT IS FOR IMFORMATIONAL PURPOSES AND I WILL 
NOT BE HELD LIABLE IN THE EVENT THAT YOU MESS SOMETHING UP. YOU HAVE 
BEEN WARNED.
Sorry about that. Like I said, I had to say that. If you're in any 
way uncertain about your ability to do this, contact your local 
computer service center and have them do it for you. 
Requirements:
1.      Large Phillips screwdriver.
2.      Jumper to connect across the ID pins.
(Try local radio shacks or computer repair places, or dealers. They 
should also be the same jumpers used in such things as ethernet 
cards for IBM's. If worst comes to worst, borrow one off another drive, 
but make sure you don't create an ID conflict in the process.)
Procedure:
1.      Open computer. (This one takes some fiddling.) Basically, there
are two round things on the underside of the front of the case 
(they're darker grey than the rest of the case). Push them up, slide 
the case forward.
2.      Remove the three metal shields from the front of the unit. Take
careful note of how they are in there. It's easier to pull off the 
small ones first. And when you reassemble it, it is IMPORTANT to 
put the large, wide one in first, before the smaller ones, or they won't 
go back in correctly.
3.      Disconnect the Hard Drive and floppy drive. There are two
connectors on the HD, the SCSI cable, and the power cable. Disconnect 
both. There's only one cable (ribbon type) on the floppy drive. 
Disconnect it, too. Since each one should only fit in one direction, 
so no need to worry too much. But when you reassemble it, I think it 
might be wise to make sure you use the same SCSI connector (the 
one on the end of the cable, not the one in the middle). Just a 
sneaky suspicion, since SCSI is so picky about termination and all. :-) 
(* NOTE: There is no need to touch the disc drive, or to remove any
cables! Just lift the tab underneath the SCSI cable of the HD and
slide out the HD (the cable is more than long enough). Flip the drive
upside down and proceede as in 4)  gerald@iram.rwth-aachen.de*)
4. Look at the sides of the upper tray that holds the floppy and HD. 
There are two white latches. Pull them towards the center of the 
case until the tabs that stick out of the sides of the metal frame 
no longer stick out. Carefully and slowly slide the upper tray out of 
the machine. Then, look for a wide white flap sticking out of the center 
of the back of the hard drive's half of the tray. Lift that tab up until 
it no longer sticks through the underside of the tray, and slide the 
Hard Drive towards the rear of the tray (towards the tab). It should 
then lift. Flip the drive upside down. There are four screws clearly 
visible that hold the hard drive to its plastic tray. Take a phillips 
screwdriver and remove those four screws. Carefully lift the tray so 
you don't lose the screws. 
5.      You should now be down to the circuit board of the drive. To the
rear (connector end) of the drive, there is a block of jumper connections 
(five pairs). Ignore the two pairs that are labelled PK and TE. You're 
concerned about the ones labelled A0, A1, and A2. Connect the jumper 
across your choice of pins. Since none are jumpered across, the drive 
is assigned to SCSI ID 0. With A0 connected, the drive is on SCSI ID 1, 
A1 = SCSI ID 2, A2 = SCSI ID 4. (It's binary numbers, in case anybody cares.)
6.      Place the HD sled back in position and insert the mounting
screws again.
7.      Place the HD sled on the main tray, about half way back, so that
it drops into place, and slide it forward until the latch clicks into place.
8.      Slide the tray back into the machine, carefully making sure that
the plastic tray slides between each pair of metal guides on the 
sides of the case, and connect the data and power connections for 
BOTH DRIVES. :-) You'll have to push pretty hard on the power connector. 
9.      Replace the metal EMI shields on the front, large panel first,
followed by the two small ones.
10.     Slide the top of the case back into place until the front latches
both snap into place.
11.     Boot in MacOS and change the lilo.conf file in the preferences
folder to reflect the new boot location (the letter refers to the SCSI 
ID, in case you don't know, where a is ID 0, b is ID1, etc.). 
12.     Reboot into MkLinux.

<Deleted kernel info and mention of keyboard bug that no longer apply>

12-19-97: If necessary, you may be able to steal jumpers from another
drive, such as the CD-ROM drive, however at least one person noted
that in some cases, the jumpers are of a different size.

After you boot into MkLinux, your /etc/fstab will need to be updated 
to reflect the new location -- and fsck will puke and throw you into 
single user mode at boot time, because it will try to read from a 
non-existant drive at ID 0.
To mount the root filesystem read-write, you must first know the root 
partition's location (get that from lilo.conf, which you should have 
updated according to the other set of directions). 
Then, type:
mount -nw -o remount /dev/sdxx
(replacing the xx with the appropriate letter and number). 
That will mount the root partition read-write. Then, use vi (you do know 
how, right?) :-)
vi /etc/fstab
Some helpful hints for any vi newbies:
i - insert mode (before cursor, a appends after cursor)
escape - leaves insert mode
arrow keys work in either mode.
To delete a letter, hit d followed by space while on top of it. To 
replace a letter, hit r followed by the new letter. To replace several 
letters, hit R (capital) followed by the new letters. 
Note that when I say letter, I really mean any character. 
To save the file, leave insert or replace mode (escape), and type 
:w (colon followed by w). To quit vi, it's just :q. 
Then, type exit and your system will reboot. Boot into MkLinux again 
and things should behave normally.