What if the brakes are on? There's only two filaments in there. You need the controller to tell the side the with the turn signal on to cut off the power for the brake lamp so the light will flash. Otherwise you are just going to muck up the system. You can always built a simple circuit for each side to do this for you if you don't want to spend $50.
2001 #62. Ohlins rear/valves, Micron high mount, HyperPro damper, SharkSkinz, Tyga billet triple clamp, Tyga Carbon Fiber fender and hugger, Ti bolt/custom subframe/alien motion 8 cell diet, 15/41 520, COP conv. PCIII, Venhill lines, modified air box, turn signals in headlights...<deep breath> ZG Touring windscreen, Tech G rear sets, CRF450 rear master w/HRC cover, Tokico 6 pots w/V-pads, CRG Bar end mirrors, PSR Shorty levers-use only clutch, wanna-be basic racer paint, Roman Gold PC wheels