You'll need an additional hydraulic circuit (spool) to control the grapple ram if you don't have one already. Or you can use a diverter to switch between the loader curl rams and the grapple ram.
Then you just pipe from the 2 outputs from that extra circuit through quick connects to the grapple ram.
I'm not familiar with your tractor, joystick or hydraulic system, but a photo would show which bits you have, and which bits you need.