elsewhere, ytrewq noted that 'optimal' conversion of thc-a to thc occurs at 248 degrees F, takes one hour.

http://boards.cannabis.com/concentra...ml#post1963885

as it happens a pressure cooker at 15psi has an internal temp of 250F.

searching for 'pressure cooker' led me to goober328, who did a test at 10 minutes, said it worked.
http://boards.cannabis.com/concentra...ml#post2118539

i mixed 1/8 oz of regs (deseeded, processed in coffee grinder until flour-like) with 2 T of glycerin in a mason jar, cooked it for an hour. added 2T of boiled water, after filtering, the resulting liquid is golden, tasty, and effective.

it's a pretty clean high, i highly recommend this process.

i wrote up a recipe, it is here:
it's me ~birthday, here's your present (cannagliss 1.01 - the recipe) : trees