How to glue and frag on a big sps colony ?

[Casey8]

I have an 8"x10" sps colonie that I want to glue to my top rock. It is at the bottom of the tank right now and it leans on the back glass wall. I have tried several times to glue it on the rock with Tunze epoxy, but this coral is so big and extremely heavy, no glue could hold it. I also want to cut some of its branches, but the diameter is over 1 inch wide, some branches are about 2" and there is no tool that will open wide enough to cut it straight across. I don't want to take it out of the water and chop it with a big knife like a butcher. Can anyone here tell me what is the best way to glue it on the big display top rock and how to frag it ?