Alright so this is my first post and I think It deserves to be here.
Ok the first time I did this it was an accident, but I have redone it 3 times on 3 different accounts.
Ok first start off by deleting Your already made char on alliance or horde. EG I deleted my 70 nightelf hunter.
Second create a fresh horde/alliance char, opposite of your main, and log in.
Third open a GM ticket saying "I deleted my Main I dont know what I was thinking".
A GM will soon whisper you asking about your problem. Restate what you typed in you ticket.
He will soon ask What race, level and class. Just tell him the Class and level Do not specify race.(also good to park you newly created char in a nuetral zone)
After some Gm roleplaying and such He should reinstate you char, and keep your horde/alliance you just created.
So now you have both only one downfall to this you cannot create any more chars on that server.
This is really usefull for conversing with horde/alliance friends.
I dont know how clear I was If you have any questions Pm me.
Ill post a SS soon