That stuff grows like weeds... are you sure you want to frag it?
The easiest things to do is just either :
1) brake a small chunch of rock off and place it in another spot in your tank with the edge of the colony touching up against the new rock. It will soon spread onto the new LR
2) Basically the same as above but instead of braking a piece off, put a small chunck of LR touching up against edge of the polyp colony and it will soon spread onto the new LR and you can then move the new frag to another location in your tank aftarwards by just braking it off.