"share the successful story so that others can see and reference
the basic solution went as follows:
looked up the model number on the manufacturer's site. found a schematic for the drive in question. in this case it was a seagate st11200n 1.2G manufactured in 1992. the schematic listed there showed how jumping the various pins on the drive would change the id numbers. it was totally in line with what an earlier poster (gerbil) had said. thanks gerbil.
from that point on i had to call a friend to find out what was meant by "jumping" the pins. can you tell i'm not very adept at basic electronics? well, i'm not--but a little determination went a long way. there are small plastic things--almost like tiny sheaths--which sit down on the pins themselves. if you cover those pins in pairs in certain ways you change the id of the device.
once i had an id that i wanted, the rest was elementary--reconnect the drive, boot from another, and voila! the second drive was readily mounted and waiting for a visit with TechTools.
after about an hour the drive mentioned above died. it made a sound like an alien sighing and then died. i couldn't re-format it, i couldn't write to it. i took it out immediately, thinking that it could potentially mess up the directory structure of the other, original drive which was on the same bus. am i wrong in thinking this?
whatever. i found another cheap drive and repeated the steps listed above, and it has been pumping along fine for days now.
so a long story, i know, but hopefully someone else will find this thread if they run into the same problems.
a very nice mac!