First, check out this post to learn about .pak unpacking:

http://www.larian.com/forums/ubbthreads.php?ubb=showflat&Number=505777#Post505777

The file you're looking for is Character.xlsm, which should be located in the Public/Main/Stats directory of wherever you extracted the .paks (I just used a folder called "EditData"). Most of it seems pretty straightforwards, though there's no documentation yet on a lot of the specific tags or columns.