well his diagram is correct, you can get two diodes at any radio shack or the like. all they are going to do is prevent power from going back down the other side.... example, left signal on, power will only feed the indicator, but if there isnt a diode in place on the right side, you will feed power back to the right blinker (not good)
so get 2 diodes, and some heat shrink (this is assuming you have a soldering iron and solder) solder diodes in place with the stripe (cathode side) going toward your indicator panel. heat shrink em, voila!