I tried to melt some 476 in a microwave but I didn't like how it was going..... it was taking a lot longer than I thought. I finally just put the glass measuring cup into a pot of boiling water.
I now have a cheap metal strainer that fits into the pot of water and the measuring cup sits in that....... my idea of a cheap homemade double boiler.
FYI (if you didn't know already), P21S and #16 was what started the
wax melting movement a couple of years back:
http://autopia.org/forum/detailing-product-discussion/49008-new-p16s-carnauba.html
Go Cats