Hey there,
You might want to take a look at my
homepage where I have some photos from when I did this to my "Yikes!" G4 PCI machine.
Given that my motherboard is based on yours, I think the placement of all components, including the processor, would be identical. The one thing that might make things easier for you is that your heatsink is smalller than mine.
I dunno, I know it ain't exactly pretty but I stopped caring about what the machine looked like when I saw the QuickSilver G4's (they made mine already seem dated in comparison). Zips are worthless IMO, though not quite to the point of floppies. And, there's no guarantee that "the other" computer is gonna have one. They're guaranteed to have a CD-ROM, that's for sure.
The performance of this drive just in normal reading of CD's compared to the OEM 8x DVD ROM drive is great! Yeah it plays DVD's but at the cost of being slow overall. I can RIP mp3's from CD 5 times faster on the CD-RW. It's become my default drive for most stuff. Hmm, I wonder if iTunes 4 will support dual-drive ripping? That would rock...
[EDIT] Oh about materials. I got the piece of aluminum to use from a home improvement store like Home Depot. Aluminum is a dream to work with (compared to steel or copper) when you don't really have the proper metal bending tools to work with. All you need is a hard flat surface with a good edge on it. Hang the sheet off the edge, hold down tight on the part on the bench, and push the overhanging edge down and in with a quick thrust--perfect crisp 90˚ bend. Steel and Copper would laugh in your face. Stainless Steel would eat you for dinner, lol. (worked 2 summers at a sheet-metal business.)
As for attaching it, you don't really need to use pop-rivets. You could just use small machine screws as well. Just drill the holes in the 2 pieces a little small, then screw the screw in with a little force. Aluminum is soft enough that you can basically tap your own thread with the bolt (or machine screw).
Anyway, hope this helps...