Making Pumpkin Preserve
This site recommends washing, slicing in half, removing seeds, slicing into 1 inch slices, peeling the skin, then chunking, and giving each chunk a brief boil for 2 minutes. Then going on to pressure can the product. It cannot be safely preserved with out pressure.

http://nchfp.uga.edu/tips/fall/pumpkins.html

And I hope you save the seeds and roast them! One of my favorite fall treats.