The key is indeed in maintaining a consistant pitch attitude with the cyclic. If you are sawing the cyclic back and forth to maintain airspeed (common if you spend too much time looking inside at the airspeed indicator), you will have a very difficult time holding RRPM steady.
Try this - go up to 2,000' (or higher) AGL, 65 KT and just start smoothly lowering the collective while keeping your eyes outside and maintaining a 65 kt attitude. DON'T LOOK INSIDE until a few seconds after you have gotten the collective all the way down. Then take a very quick glance at the airspeed and RPM, then eyes back outside. Smoothly make whatever attitude adjustment you deem necessary, then HOLD THE CYCLIC STILL.
At the same time you are doing this, listen to the RPM. If it starts rising, raise the collective about 5mm. Wait, listen, if it holds steady, leave the collective alone. If the RPM starts going down, lower the collective 1/2 the distance you raised it.
Now here's the trick: every time you are going to move the cyclic aft or make a turn, nudge the collective up 5mm just before you make the cyclic movement. If you are moving the cyclic forward or rolling out of a turn, lower the collective first. The more you plan to go aft cyclic or turn, the more collective you raise in anticipation. Same for lowering collective.
As long as you anticipate the RPM changes caused by flaring and disk loading, autoing the R22 is not difficult!
Hope this helps - John