Thats almost imposable to do without having half the screws fall out. You cant aim it just right because you always have to slide it to the left to get the ports on the back of the mobo lined up with the case.
The I/O shield is probably the trickiest part, i'd agree, but it can be done. Occasionally the far right-hand screws will slide out because it tips too much, but those are the easy ones.
I've got an OLD screwdriver that I'm almost certain wasn't intended to be magnetic, but somehow it is, very weakly. It can hold onto a screw completely vertical but if you tilt it it falls off. I use that, works great.