You Go Into Notepad,Open Up Pedstats.dat and Just Change His Style to grappler, there is a tutorial on this!
It's not that simple.
There are 2 ways:
1. Go to [Bully folder]/Config/DAT/Pedstats.dat and open it. Change Jimmy fighting class to grappler and set grapple reversal to 100%. After that go to [Bully folder]/objects/ide.img and change Jimmy faction to any other.
2. Bind the grapple reversal animation to a button using lua scripts... if Rise agrees to use the animation.
Check some tutorials since I didn't explain step by step how to do it, just the basic ideas.