Does anyone know where you could find a how-to guide to do this yourself? Or is this the type of thing best left to professionals?
http://en.wikipedia.org/wiki/M39_lens_mount
You could start with a T-mount adapter to get to 42mm:
http://en.wikipedia.org/wiki/T-mount
http://www.adorama.com/LNTMEOS.html
Then a 42mm to 39mm step-down adapter ring:
http://www.amazon.com/Fotodiox-M39-Adapter-Zeiss-Pentax/dp/B...
Not sure about the clearances, and you may not get infinity focus depending upon how far out the lens ends up being situated from the focal plane of the sensor.
Edited to add: google turned up this direct EOS to M39 adapter:
http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=110365260908&ssPageName=STRK
But note "DOES NOT allow focus to infinity".