The only other way would be to add a nameserver for the subdomain, but I don't think CPanel lets you do that.
Edit: Yeah, can't find a way to do it in CPanel directly. However, I can do it in WebHostingManager so maybe ask your host. I'm just waiting for DNS to sort itself out so I can test it.
EDITED: 17 Apr 2013 13:51 by PILOTDAN