LoL - love your avatar.

Yep the best way is to assign keys to switch focus. If you don't want to use the function keys, do what I did and use these 6 keys:
[Insert] [Home] [Page Up]
[Delete] [End] [Page Down]

Home is my invite key, the others are the focus keys, which also happen to match the way my monitors are set up.

Cheers,
Stealthy