Mine is  stuck to the tripple tree. To get it there I had to remove the tank and run about a tank and a half  length of bell wire(x 3) up to the head tube.

I tried mounting it to the rear fender, but I could only hear it when standing still - useless as it only helps if it reminds me if the blinkers are engaged while in traffic.

I've read that after a month or two I can disable it, as it would have trained me to disengage the blinkers "automatically".

There are several ways to do it. Easiest, in my mind, is to wire the beeper directly across the turn signal flasher. Use a low-current unit. Most electronic beepers will use less than a tenth of an amp (100 millamps). Unplug the flasher. Slip some fairly thin wires into the female connectors and plug the flasher back in. Run the wires to wherever you want to mount the beeper. Connect the wire that goes to the blue wire in the flasher connector to the negative side of the beeper, and the wire that goes to the orange or brown wire in the connector to the positive side of the beeper. MAKE SURE NEITHER WIRE IS GROUNDED. The beeper will beep when the turn signals are in use, but it will beep when the signals are not lit, and be silent when they are lit.

Theory of operation:  The turn signal flasher is a relay, normally closed when the signals are not in use. Power is applied to the brown or orange wire whenever the bike is on. Power is applied to the blue wire through the flasher. With power applied to both sides of the beeper, it does nothing. When you turn on the signals, the power is routed from the blue wire, through the signal switch, to the lamps on whichever side you selected. The lamps light. After a short time the turn signal flasher starts cycling (turning itself on and off), thus flashing the turn signals. When the flasher cycles the signals off your new beeper has power on its positive side, and sees ground through the switch and the now cold filaments of the turn signal lamps. It beeps, but its current is so low as not to light the turn signal lamps.

There are other more complicated ways to do it, including some circuits so the beeper won't beep while the brake is applied (that way you don't have to listen to it while stopped at a light). I believe there is a way in the technical section, using steering diodes and a relay.