sram grip shifter to be fox CTD shock remote lever
Just follow the twister shifter instructions, but attach the cable to the CTD actuator (same as the current remote is currently attached, on the blue actuator on the shock), instead of the front derralieur. Adjust tension as necessary using the barrel on the gripshift.

Finding a SRAM front derraileur 3-position twister shifter might be hard these days (I think they only sell rear derraileur shifters now, since 1 chainring is the current "fashion") but if you find it... it's just a cable tensioner, same as the CTD remote.