Unless I'm misunderstanding, the easiest way to share in this situation is to use a private address. The two options here are, to either use private or pay your provider for an extra IP address. It varies but some broadband providers usually leasejust one address or want you to get a business package to get extra addresses. Since from your post they said(as most do) they dont support a home netowrk(or the like), you're going to have to do it on your own with private addressing. You can usea crossover cable to connect between the 2 PCs or use a broadband router that makes it real easy.
If you use crossover you can use ICS to provide addressing and such to the client. You can also setup static address and do it all manually but you need to understand what you're doing.
If you use the router option you basicly just hook the cables in and your done. There is minor configuration issues for some providers but it all just depends.
Now on the other hand if your talking about using APIPA(or whatever the name is) that is used when there isn't a DHCP server or the like, that's a whole other ballgame and I dont recomend using it. Its not reliable enough for what you want to do. Stick with using 10., 192., or similar addresses.
Hope this helps some. This is very basic and just wanted to get you in the right direction.
Jason
