i have one of those too!
lovly piece of kit, and i've fitted it in a HTPC too
and for anyone wanting to get one but think you might cut your fingers into million pieces.
you simply dont place your fingers where the push pins are, get a flat head screw driver, go from the top of the cooler, on all 4 corners there is a slot on those fins where you can see the push pin from the top.
on those push pins, theres a groove on top, simply use flat head screw driver, push it down till 'click', job done.
same as for unlocking the pin to remove, use flat head screw driver, twist it, and pull off.
pic of it fitted inside a HTPC (excues the 'cable managment')