All you need to make your disks is the IIgs, disk drive, null modem cable, and ADT software. You would want the second cable shown on the page I linked, the one marked "
Apple IIgs, IIc+, LC III null modem".
If your PC/Mac doesn't have a 9-pin RS232 serial port, you will also need a
USB>Serial converter I strongly prefer the FTDI chipset ones, they are the most compatible and reliable that I have found, and I have worked with A LOT of USB>Serial adapters in my day (I have dealt with Belkin, Startech, and many generic chinese imports). I hear the
Keyspan brand ones are good too, I know a lot of mac users prefer them, and they get good reviews, but I never had occasion to actually try one myself.