i dont know what you're trying to do, but to get your internals out, you shouldnt need to take the frame off... all you have to do is push your sear down, and pull out the hammer, and everything else should come with it.
well you could dril out the old screw..just be very careful. that's what I woudl do if i were in that position. But i like to drill a lot, my neigbor kd dropped by (he's like 9 or 10) with his viewloader and i made him a modified trigger by drilling through plastic (wtf!!) and then using a very long screw so hs trigger would stop pulling right when it shot...i hope he likes it.