I can't believe you think everyone on the internet has read this thread, and need a pinout for something that you don't even have. You can also use a DMM for more than checking voltages.
You could trace them back to tell what they are. Based on how the 3 and 5 wire models are setup with Ground, 5vsb and PS_ON, it's probably the same way but has either 2 x Grounds or 2 x 5vsb lines, which could be checked easily enough if you used a DMM to check for 2 pins that are connected, or just looked at it for a bit. You'll get the Ground(s) figured out for sure, then the 5vsb would most likely be the heavier of the remaining traces with PS_ON being the only one left at that point.
Screwing up is one of the best learning tools, so long as the only thing you're not learning is how to screw up.
Re-mappable Wireless 360 Controller - The CGnome