I found that putting a spot of lipstick on each screw head and then placing the pre-cut piece of sheetrock against them marks where they will bulge out.
I then picked a little depression over each spot and the sheetrock lays flat.
I also us a piece of Masonite ,1 1/2" wide as a furring strip to make up for the 1/8" flange edge. Works great.
Where the sheetrock meets the shower I use a piece of "J" channel and will silicone a tiny bead along it later.
Working out fine so far. Well back to work.
![Image](http://mobilehomerepair.com/phpbb/userpix/716_DSCF4367_1.jpg)