bad idea. Rim screws are meant to go in through the side of the bead. When you air down where does the tire want to go? Away from the bead. What about the screws stops that? very little. Drag racers are worried about spinning their rims inside their tires when they air down and get really sticky. We are worried about our tires pulling away from the bead. If you use rim screws all you will do is ruin a good set of tires.
There is a guy on pirate who is puting screws in the rim. He puts them on the other side of the bead. Creating a lock between the outer bead and the screws. Problem I see with that is, when you tires roll down under low pressure, those screws turn into shredders. Also however many screws you use, thats how many times you just increased your likelihood of slow air leaks, or massive air leaks.