i have been hunting for ideas for parts for the switch. you could mount it in the stock switch gear if you want or make a small bracket & attach it to that near a leaver or similar.
some ideas
water proof hood
http://www.jaycar.com.au/productView.asp?ID=ST0590
mini switch
http://www.jaycar.com.au/productView.asp?ID=ST0300
diodes
http://www.jaycar.com.au/productView.asp?ID=ZR1018
these should all work nicely
a more expensive idea is to buy one of these
http://www.kriss.com/hazardflasher.php
if you look at the right side switch gear (where the indicators are) there is a small square plug/hole. that is a cover for a hazard switch. just need to find a switch to got into it.
a quick google shows this
http://www.kawiforums.com/ninja-500r/151597-hazard-light-switch.html
the important bit we want out of there is this
Hi! Had the same complaint about my Ninja 500, but here is the answer to it: They don't make anything for the latest models, but there are still parts available for an older model liter-Ninja. I bought this after a long talk to Kawasaki tech support: Part# 46091-1857 Housing-Assy-Control. It's a 'plug-n-play' thing. All the plugs fit, no need to replace the choke lever or anything. It takes about 15 minutes of work, and that's only because I couldn't get my fingers easily behind the front fairings. No need to take it to the dealership for expensive hourly rates.
i dont know if this will fit the ninja 300 or not, but the button looks like it will
another idea is to search ebay on "motorcycle hazard switch" and you will find one of these for under $4
http://www.ebay.com.au/itm/Motorcyc...tch-Button-/321145526382?pt=AU_Motorcycle_Parts_Accessories&hash=item4ac5c3d86e
27-07-2013 - tested this idea today, the wiring from the 250 is the same as the 300 when it comes to how the indicators are wired up. the lights on the dash also light up with it. im just waiting on the ebay motorcycle hazard switch to arrive & i can put it all together
i taped in to the wires with a positap adaptor at the flasher as well as the indicator wires
www.posi-lock.com/posiplug.html
part number EX130RR
upgraded the relay a few weeks ago in readiness for this project, im using a "tridon hd12pac"