It was almost certanly just a one-time guest appearance, so there wouldn't have been hoopla like that surrounding the announcement of George Takei becoming a semi-regular member of the cast, IMDb doesn't have the episode's full cast up yet, NBC.com hasn't posted the full episode yet, and everyone on the various Heroes' webforums I surfed through cared too much about the implications of his character's past actions (and everything else that went on in the episode) to discuss who played the role.
Feudalism: Serf & Turf