After loosening the screws, it is a good idea to use a magnet to pick them up.

I've used the Mako screwdriver kit's magnetic bit to pick the screws up.

Put the screws away in a container, where you can safely store them.

Since these screws are pretty uncommon, it will be nearly impossible to find exact replacement of them. Do your best to avoid losing these.

The lid of the Mako screwdriver kit is a perfect screw holder, as well as the magnetic plate under the screwdriver kit.