Most of the boards i've seen actually have 2 pins across from each othere that hold the NB fan in place. I 've removed a couple just for the fact that the manufacture had "gooped" the thermal compound on so heavly that it could be seen oozing out.
As far as cutting the ols sink, never tried that although as a contractor I have at least a half dozen tools that would do the job. Since there aluminum perhaps a band saw. Maybe a dremel with a cut-off wheel? I could always pull out one of my saw-zalls and cut it, though the finish would look a bit hacked.
As far as the Mofsets they are located next to your ATX power connector.
Here's a link that should be of help;
http://www.overclockers.com/tips1027/
WB