Here's how I got mine working:
Hooking up the external SCSI drive that came with my Mac Plus to my G4's SCSI bus and copying over formatting software. Use Silverlining by LaCie. Obviously you don't have another Mac with a SCSI Bus, again, somebody on this forum would probably be capable of sending you a disk with aforementioned software, all you have to do is ask around.
After you get the formatting software taken care of: connect the zip drive to your SCSI bus, preferably the last in the chain, so you can enable termination. I also recall that if you put any more than one thing in the bus you need double termination, hopefully this won't be a problem, as you should only have the zip drive in the bus. After you get everything connected, boot the machine, run formatting software, and format the zip disk (DO NOT USE LIDO AS YOUR FORMATTER! If you use Lido, you won't be able to boot from the zip). Then you may install System 6 (or anything else) and have a zip booted Plus.
-tm512
EDIT: I forgot that you had only 1MB of RAM in it. System 7 will refuse to boot, but hopefully you won't want to use it to begin with. My real suggestion is System 3.2, Finder 5.3 for sheer speed, or System 4.x, with Finder 6, I forgot exactly what version was, for max compatibility. Again, ask around for this crap. :b&w: