I would try to pickup a used soundcard. Lots of older cards supported ADAT lightpipe.
Alesis used to have a cheap card for ADAT transfer but I can't remember the name of it.
Other possibilites... RME hammerfall cards, M-Audio DIO 24/96. It might take some digging. You might ask on Yard Sale too.
I have an SEKD Prodif96 Pro card that has that, but you have to use Win98 drivers, (or NT). I'll take $50 for that if you are interested.
I could not get it to work on Win2K, so I doubt it would work on XP. But if you have access to a Win98 computer that would be one way.