I've done it and it's fantastic! I halve the pumpkin, scoop out
the seeds & fibers, then bake with skin side up in about 1/2 inch
of water until the skin is leather tough. then, puree! If it's
too thick, you might have to cook it down a bit on the stove.

I just used the Carnation recipe and substituted the cooked
pumpkin for canned.. GREAT!