Here is the cook link from XDA:
http://forum.xda-developers.com/showthread.php?t=366333
and here is the user link from XDA:
http://forum.xda-developers.com/showthread.php?t=366337
It was more or less worked out by Sleuth255 on XDA. I have a pretty good grasp of it from the user stand point, although I don't really know anything about cooking ROMs, so that part is a bit beyond me, but if you need help, I can at least try.
It basically allows you to write a file that will install any cabs/xml files you want so that you can automate a good amount of your set up after a ROM flash. Very necessary for the HTC users, as a lot of us are flashing near daily, and installing 20 cabs and changing 20 settings by hand is really annoying, as I'm sure you can imagine.
There is also a thread here on PPCGeeks,
http://forum.ppcgeeks.com/showthread.php?t=59566, where a lot of really good info is located.
Let me know if you need any more info, I will see what I can do!