Rob Macks posted a great summary of magnet installation on this BB a few months ago, If you run a search on magnets you should find it.

I used his magnet size (3/8") and spacing (3-4") to put magnets in my S&G. I used a 1/2 forstner bit to cut holes in the hatches to epoxy the magnets into, then covered them with a small pice of 4oz glass and epoxy. I used Vaclav's method of building a hatch lip from glass and epoxy and buried the magnet twins into the lip as part of the first layer.

I have still to add the gasket around the hatch lip. I could post photos if that would be helpful.

grant