I'm currently doing this, but it will be long before I'm done since my work and social life takes way too much of my time. I'll be posting tutorials as I progress with my project. I have already started a thread on fitting an pico sized ATX PSU inside the case to fuel the needs of those cards. Tomorrow I'll be posting the wiring from the ATX PSU end and once I'm done with the mods I will do stress tests with temperature measuring.
I have an idea for the cooling also so be sure to check out the tutorial sections in the next coming months.