WoW now (from 5.0.4) defaults to DX11 mode. You cant force AA level for DX11 from CCC, you can only change AA mode (multisample/adaptive/supersampling).
So, pick AA level in WoW (x2/x4/x8), and set AA mode in CCC to your liking (I use supersampling).
If you want to force AA from CCC, switch WoW to DX9 mode.
Sorry I don't know about crossfire, have single card now.