I was tired of having to reach over and hit the resume switch and wanted it on the hydro handle like the newer machines. I couldn't find anything on how to do it or showing how anyone had done it so here are some pictures of what I did, hope it helps someone else
1. I used a button and wiring off a flashlight (some people use them under the barrel of ...), I had to break the part of the button off that was on/off so it would only function as a momentary button. I likes it because it was rubber like the handle and it
had a large pad which made it easier to push from either side.
2. The handle has four screws that are removed and the cover splits apart, its all sealed so nothing to worry about. I drilled a small whole in the side of the handle where I wanted my button to be, and ran the wires inside to keep it clean and to prevent
them from getting pinched while functioning the handle. There isn't a whole lot of room in the hydro handle for them to fit so pick something with thin gauge wire.
3. Then cut the current Atu switch off and pass the wires up through the armrest where the main wire loom comes in and splice your wires together inside there. The orientation shouldn't matter since its just a momentary switch.
4. I then used gorilla glue I think, or epoxy, to fasten the button to the hydro handle and zip tied it tight until it was dry.
I ran it all last season without a problem. I like the location because I can hit it with my thumb or with my fingers around the backside no matter how my hand is positioned without having to take my hand off the hydro handle at anytime.