It's stickied in the General section of the forum, and on the wiki - Focusless, Targetless, Leaderless system. There are a lot of variations. Mostly it's designed to work with keyclone, but I bet you could get clever with the idea behind it, especially with only two characters. The intent is to set up your alts so you can switch primary control between team members seamlessly...with only two, you could probably work out some clever macros or UI setup, maybe /click or something. But how you would need to work it out depends on the details of your setup - which I have no knowledge of.