Hey no problem. It may well turn out that you can't do what you're trying to do with the 2 wire - don't forget you're making it do something it wasn't really designed for !
You may find it easier just to go out and buy a wireless router - something like the
linksys wrt54gl is what you are looking for.
These devices have a Wan port that connects to your RCN cable modem and enables you to share the connection between several computers. The are specifically designed to do what yo are trying to do.
Another simple solution may be to see if your ISP provides an "off the shelf" solution i.e wireless router/modem that may be just "plug and go".
Personally I like to see if I can utilize whatever I've got lying around but that's probably just my hacker mentality !
Damn - michaelk beat me to it !!
Let us know how you get on and good luck.