I think those damn intel fans with the four corner press-n-rotate "screws" were the worst; every time it felt like you were going to crack the mobo in half...
I just replaced a cooler like that yesterday morning (with another one with the same screws)! Pretty annoying to work with.
Funnily, those screws also sort of fit into the grid on the back of my computer case, so I mounted the old cooler externally, and it helps draw the hot air out. No reason to throw away a good PWM-controlled fan if you have a free connector on the motherboard, after all.
And after a few minutes of trying you've forgot in what direction you are supposed to screw them ...
If you're doing it for the first time, try a few times without the thermal paste so you get the feeling of it. Then the pins will also go down easier when you do it for real.
