keyclone makes this pretty simple.

run keyclone on all the machines... determine which you will call your 'main'.. and put the ip and port in the auto-connect field on the general setup panel. the ip and port of your main will be in the titlebar of keyclone on that machine.

by doing this, whenever you start up keyclone on all your machines, they will automatically connect to each other. pretty simple. you can even set it up such that keyclone will start your wows on those machines... leaving you at the password prompt on all of them. if all your passwords are the same, then you only have to type in 1 password, and all your wows on all your machines will log in