[Wikihow suggests][1] using a rolling pin to crack the (cleaned, dry) seeds, then boiling for 30 minutes so the pepitas are released from the hulls.

Skim the empty hulls out of the water, then drain the water off of the pepitas and pat dry.  Now you can eat the pepitas as is, or roast and flavor them.


  [1]: http://www.wikihow.com/Shell-Pumpkin-Seeds