My enclosure came with 8 total mounting brackets. 4 each with keyholes in opposite directions. Mounting was pretty easy though. I put a 3/4" x ~2.5" board of an appropriate width on the wall with two holes on each end directly over a stud. 3" screws keep it in place. I used lag screws that fit through the keyhole (take the bracket to home depot).
As far as alignment, mount the top first including the board and lag screws. I put the lag screws a bit above center so the bracket is mostly centered. Then hang the panel and mark where you want the bottom board -- mount that, and then finally put the bottom lag screws in place.
I painted it then since I was painting that wall anyway. The 'buttons' are just filling the screw holes.