I have a network interface on a linux based computer acting as a router that gathers 2 dynamic IP addresses from my ISP using interface aliases.

So I have eth1 and eth1:1. Eth1 has ip x.x.x.x and Eth1:1 has ip y.y.y.y. Assume for a moment that I already know the two ip's so they are now basically static ip's (they have never changed in the month I've had this up.

I have two computer hooked up that I each want to use one of the IP's. I would assume this would be accomplished via iptables...but I don't have a clue. I'll work on how to script it so that it does it all automatically...but I don't know how to do it if I know the ip's that our allocated

I don't understand what you are doing. Only thing to remember is iptables does not use ip aliasing like ethx:y. For it to work you need to use the IP of the interface of ethx:y.

Brian