Procedure goes something like this - Remove the seat, tank, left side cover and left engine cover. Remove the radiator cap and (with a drain pan underneath) remove the drain bolt. (It is the one closest to 6:00 on the Water Pump - the only one with a washer beneath it.) Hold the bike upright so it all drains. I flushed it by pouring a little fresh coolant through. Clean off the drain bolt and re-install (9 lb-ft) with a new sealing washer (PN #90463-ML7-000). I took the reserve tank right off the bike by removing the red siphon hose (bottom of tank), and the plastic filler neck. Remove the bolt and it slides right out with the other two hoses still attached. Dump the old stuff out, clean it up nice, and re-install. Here is the tricky part - refill the system (Honda HP coolant) and start the bike . You need to do this with the gas tank off and the cap off the cooling sytsem. I have a gas can with attached fuel line so I can run the bike with the tank off. Let it run for two or 3 minutes. Blip the throttle to purge any air from the system, you will see that the thermostat opened when the coolant starts to flow. Top off the coolant (bike upright) and install rad cap - dont forget the refill the reserve tank as well. Button everything back up and go ride.
I found this little write up for you, I hope it helps