Look up "mouse broadcasting" for ideas on that. I think it's discussed in threads about accepting quests and such. Octopus is what I use for it. Wireless mice is what I used to use for it. Both of those work fine.

Regarding the addons for group wardrobe and such, I looked but the only one I can find is Multiboxer V2. I thought there were others but that might be what you're after.