Hi Branden,
VultureProg was mentioned - even a DIY emulator would be fairly straightforward; that's a nice microcontroller project.
That seems a bit overkill, but then again flash chips seem to be more expensive then microcontrollers these days. I don't think I'm up to working on something like that right now though.
Not sure if that might be what you're looking for, but I have successfully used a memSIM2 emulator on a similarly old platform. It's basically an SRAM, some level shifters and a microcontroller to program the SRAM via USB. There's some open source software that can talk to the device; never tested the vendor software. Beware though that you must make sure that there are no +12V on the two pins that might be used for programming voltage; if +12V is present on the socket on the mainboard and you plug the emulator in there, it'll fry the emulator. I ended up plugging a socket with those two pins removed between the socket on the mainboard and the emulator.
Regards, Felix