I don't have anything specific for the RX3 and I've never done a manual cleaning of one but this video is pretty good. Focused on a BMW but would seem to me to be the same process:
Looks like it would require building a small rig shown in the video. Beyond that I'd give a call to Gerry at CSC as he's awesome to speak with. Or, a new one looks to be $82.80.
http://www.cscmotorcycles.com/Fuel-I...-p/z35-114.htm I ALWAYS run Lucas upper cylinder lubricant and cleaner in my fuel and then every 4000 miles I run Lucas injector cleaner for a tankful. All in hopes that this never happens!
Joe