For OSX disk dumping, I used disk utility to mount a floppy and create a *.dmg from it.

From there I had to use this http://forums.macresource.com/read.php?1,160169

just converting a DMG to an IMG.

I FTP'd it over to my 8.6 G3 and it mounted in 6.3.3. Now my goal is to get it on the SE (7.0.1) which also has 6.3.3 and see if I can't mount it, open 4.2 and 'create an image'

the goal is to skip the G3 middle man. That's about the easiest way I could think to do it.