With AV enabler addon (link) you can all queue up at the same time, obviously you need to get on skype or vent with eachother. What I prefer to make premades however is (and a method that is prolly easier as a boxer) ....

1) Get with 4 other multiboxers on skype
2) Everyone has PvP random bg screen open
3) "Leader' calls out:: 'mouse over queue-up button, ... queuing in 5,4,3,2,1 ... now'
4) Everyone queues his/her own team at the exact same second
5 When queue pops you check if everyone got it, if not do it again

pretty good chances you can make pretty big premades like this