File sharing between XP Home and OS 10

I am trying to share file using a Windows XP Home computer and a Mac Mini and a crossover cable.
The two computers are not on a LAN or the Internet.
I can ping either computer from the other one with no problem but I can not share files either way. They are both using a 169. IP address and 250.250.0.0 subnet. I have tried to set up a network place from the Windows box using the IP address of the MAC as the destination but it didn’t work. I tried from the Mac but it wanted the IP address of the DNS server, which doesn’t exist.
I know I could put a router in the middle but the customer doesn’t want any more equipment to generate interference. There’s already plenty there.

AG