Heatsink Head Scratcher

I'm looking into buying this Noctua cooler https://www.amazon.com/Noctua-Low-Profile-Cooler-Retail-Cooling/dp/B009VCAJ7W/ref=sr_1_3?ie=UTF8&qid=1469752094&sr=8-3&keywords=cryorig+c7 but one thing just gives me a head scrather. So you install the thermal paste, place the heatsink onto the CPU, and then from behind the motherboard you screw in the screws. My question is, how are you supposed to screw in those screws while keeping the heatsink on the CPU? WOuldn't it require like 3 hands, two to hold the heatsink onto the CPU and life it up, and a third to screw in the screws?

In my case, Cooler Master Elite 110, there is not an opening at the rear of the motherboard, so I have to take the motherboard out of the case in order to install this cooler. I just don't know how to screw in the screws from behind the motherboard, since that requires lifting up the entire motherboard and then I gotta hold the heatsink in place at the same time and everything.
 
Solution
A little smear is OK - the pressure from screwing the cooler down will equally spread the paste (especially if you tighten the screws in a cross-wise pattern).
Well in that video it looked like he had a bit of trouble getting the holes to align with those of the motherboard. I just don't want to be fiddling around and causing the cooler to be smearing the thermal paste all over the place, you know what I mean? But, it seems like placing it on there and flipping it upside down is most ideal.