I copied this from a site on the web: It should help
You will first need to remove the top cover, # XXXXX in diagram below. Once off there will be 4 screws securing the control to the dash, they may have nuts on the back side. Remove these and there should be enough slack in the cables to pull the control out of the dash. You may have to cut some tie straps under the dash holding wires to get the slack you need. You may also have to unplug some wires, such as the trim control switches.
The dual control is basically two single controls bolted together. There should be 3 phillips head machine screws holding both halves together. Once apart you can remove the black plastic covers from each side and you will see the cables and connection points, #15 & #22. The adapters on the ends of the control cables will be secured by a c-clip. Remove the clip and disconnect the cable.