Try looking at:
http://www.microscopy-uk.org.uk/mag/indexmag.html
and do a search for photography. For example, I saw an article on using
an enlarger stand as the support for the camera (perhaps on that site).
Also follow some of the links on the Micscape site.

There are numerous references to this sort of operation on the net -
I've got a lot of files of them myself. Unfortunately, all of my
bookmarks, files etc. are on a no-longer-connected PC, and I haven't had
time yet to move them to my new, sexy machine.

If you still are stuck, I can dig up my files for you.

Joe
(Correct email address is: jdella-feraATmmmDotcom)