I assume you want to do just an antler mount, correct? (No shoulder,right?)

#1) First cut about an 1 or so from the back of rack straight down, to about mid line with a sharp hand saw (mitre style saws seem to work the best). You should cut down into the ear area, better to go a bit further.

#2) Then cut on a 45 to meet the first midline cut(in the front forehead area). Make sure to cut all the way through. The rack should just pop out(do not force it, I have seen many break at the join in the skull), remove the grey matter and skin the hair off. Boil in salt water or let it sit in salt warm salt water for a few days. Then clean off any matter, hide and let it dry before doing a mount. I actually will cape the area before cutting so I can see where I need to go, but it isn't required. Be careful when trimming a soaked skull it can be weak for a period and bust in the join..so don't pull or pry.

The flat edge can be mounted to a plate you make or buy, I pre-drill a hole and place a screw into my mounting plate. Then some nice red, black, blue, green, velvet and hot glue gun coupled with a nice plate stained & varnished you have a ready made mount for the trophy room that will cost next to nill and you did it!!!!! If you just want to hang the skull, place a eye hole screw and hang..great for the garage, etc.

Now if this not what you are asking, I just typed a lot of useless stuff.