It's quite simple, really.
1. Make this macro,
Code:
/script BattlefieldMgrEntryInviteResponse(1,1);
2. A few seconds before WG starts, start spamming it.
This effectively auto-accepts the WG queue as it's much quicker than a normal person just clicking 'Accept'. I'd estimate that if no one else is using this macro (and there's a good chance of that as this command isn't really documented anywhere yet) you can get leader almost 100% of the time.
You're then free to kick people as you choose, or use something a bit more nefarious such as Grief Wintergrasp - Mass Disband