Welcome to the forum. Here is what I did on my 450 when I first got it. I, like you, have a disability that prevented me from operating the rear brake pedal with my foot. I looked at a parts diagram and your Bruin should have the same cable and spring connected to the rear brake pedal. Just disconnect the spring from where it hooks to the pedal, and reconnect it where I have shown so that way it keeps enough tension on the cable to allow you to shift. If you ever need to change it back, just reverse the process in no time. All this is right behind the front right wheelwell.
Edit: don't worry about anything electrical. the lockout is strictly a mechanical system
