Well it all depend on how committed you are to the project!..
Finger throttle is needed! I recommend the ->
Munster Finger Throttle (I always thinking that everybody uses the finger throttle just because I'm using it my self!..

)
Parts needed:
277002335 - Handlebar (Manta Green) (Other colors are available!)
277001946 - RH Handle Grip (Deep Black) (Other colors are available!)
277001958 - LH Handle Grip (Deep Black) (Other colors are available!)
277001863 - Insert Grip Handle
234062600 - Flat Washer M6 (Stainless)
250000002 - Hex. Screw M6 X 30 (Scotch Grip)
277000203 - Black Cap
Seadoo Spark Trixx Parts diagram (Steering)
The problem with this setup is that you loos the heated grips unless get the heated grips from Seadoo as you can't move them to the Seadoo handlebars! I don't think the break assembly would interfere much! and if you use the "Seadoo none heated grips" just trim them to work!..
I would not personly do or recomend all off this but yeah you could still do it!...