OK, for a faction change, here's the only method:
1. Ensure level 55+ toon is on a PvE or RP-PvE server
1.a If not, transfer wealth from bank mule to level 55+ toon
1.b PCT level 55+ toon to any PvE server
2. Roll new DK on horde
3. Transfer wealth from bank mule to new DK
4. PCT to new high level server if said server is PvP, if it's PvE you should be all sorted after step 1.b
5. ???
6. Profit
7. (Optional) Get pissed off at the step ???->step profit meme and think of creative insult to point out intellectual limitations of people amused by it.
Basically if your draenei is on a PvP server, it will cost you two transfers if the destination realm is PvP, only one if it is PvE (since you can transfer the level 55+ toon directly to the target realm).
Oh, and if you can, don't hesitate to take advantage of free realm transfers when available, you can move any toons as long as it doesnt' violate the PvP server rule saying that you have to have only one faction per server per account on these.
Edited, Dec 9th 2008 4:18pm by Alastaironsiren