Peter, there is a long thread here in the DIY sub-forum on building a cold finger cooled DSLR. It was started by Rowland ( rcheshire), and is probably in the archives by now but it covers everything, including materials required and possible sources, how to do it, how to build the temperature control box using a PWM, testing results, etc. Recommended reading for anyone considering it. It is worthwhile project, and totally eliminates thermal noise in your images.
For camera disassembly and mod instructions i recommend Gary Honis' excellent website instructions for various Canon models.
Found the cooling project link here:
http://www.iceinspace.com.au/forum/s...d.php?t=132498