Ahh.. Perhaps you could wrap the head in tinfoil then mold on it. The tinfoil won't stick to the head, and should peel off easy enough from the hair, or you could just bake it with it on there (I hope ._.)
You can boil sculpey as well! If you don't want to risk baking the hair or head, you can boil it! The plastic will get soft, but it will harden after it cools, and it won't flat out melt like in the oven.
Waiting for: Series 8, Sky Crawlers, NewType Yuki, WF2008