Here's the disguise system primer:
@disguise set name Arthas
@disguise set description The Lich King
@disguise save 1
@disguise apply 1
@disguise remove
Use save to save a disguise to a numbered slot. You always have 1 slot, but with more points comes more slots.
Use apply to disguise yourself, you must specify a numbered slot.
Use remove to go back to being un-disguised when you're done.