well, you will find all you need to know at thedentedhelmet.com just click on the forums link there.
But I actually have put my helmets in the oven at like 125* on preheat
and then i reshape how i need it.
Ive done that w/ fetts, and biker scouts...just make sure you keep an eye on it, check on it every few seconds...so it doesnt get too hot too quick.