I don't think you have to go through the trouble of drilling 1/2" holes
to make the floor float. It's just closet doors. If you ever want to
change something in the future you'll have those holes exposed and have
to fill them in. I would drill a pilot hole and then use regular #6 or
#8 wood screws.You should be fine. Just take into account the height
difference you'll have now with the mirror doors now that you put
laminate flooring down. It should not make a difference anyway if you
can adjust the rollers on the doors.