As promised, I checked in my ever-growing book shelf and found two
references on steam dewaxing:
No. 1 is found in Practical Casting - A Studio Reference, by Tim
McCreight. Published by Davis Publications Inc, Worcester, Mass.
No. 2 is found in Lost Wax Investment Casting, by C.W. Ammen.
Published by TAB Books, Blue Ridge Summit, PA
I have never tried this myself but it seems wonderfully simple, if
one uses some common sense. In a nutshell, it seems all you have
to do is somehow position your investment/wax over the water and
bring the water to a healthy boil. The important thing seems to be
that you must have this all enclosed somehow, perhaps by a metal
pail, or some other suitable-yet-simple covering.
PS: I had trouble finding the Ammen book, originally, but eventually
tracked a copy down in a university library. If I can recall, it might have
been out of print. I found my copy in a used book store.