This is fantastic stuff, I'm going to put much more effort into moving my weight in corners.
If you are serious about learning this technique, read up about it first so you understand why, and practice at comparatively low speeds on as deserted a road as you can find.
Here are a couple of basic articles on the subject that provide useful information:
These articles are long on why, but short on how. Some fundamental principles:
1 -- All your moving around on the bike must be done exclusively with your legs! The handlebars are there for steering, not holding your weight (that's right, not even while braking), and if you are using your hands to help move around you are steering even if you're not aware of it. This brings up a very important point: If your bars are too far forward too much of your weight will be ahead of your CG, and it will be nearly impossible to move on the saddle without using the bars, compromising control. Basically, your setup should be such that you should be able to lift your butt off the saddle whitout using your arms to help. If you can't, either your pegs are too far back or the bars are too far forward. As the bars are easier to move than the pegs, find a pair that will position you properly.
2 -- When you shift your weight in the saddle, the bike will want to turn in that direction. It's a natural consequence of the combined bike / rider CG shifting. Don't let it! What you have to do is apply a small amount of pressure on the bars to keep going straight until you want to cut in to the corner. It's not that you are not telling it to steer, it's more you are telling it not
to steer. Practice this on a straight stretch of road until it becomes instinctive.
3 -- Move your entire upper body, not just your butt. The whole point of this is to change the combined CG to the inside of the turn in order to go through the corner with the bike more upright than would normally be the case if you were centered on the saddle. If your head is still centered, the CG is not shifting nearly as much as you may think, and you may lean far enough to drag hard parts unintentionally. Think "biting the mirror", though you dont have to be perched over the bars every time you hang off. More on this later.
4 -- Be as smooth as possible. This does not mean slow, just smooth. Any jerky moves will upset stability as you are setting up for a corner, and unstable is the last thing you want at this critical time: you have enough to worry about! To assist in this try to stay in contact with the saddle while moving across it -- slide, don't jump! As you get more proficient at it, you will notice your moves getting quicker but the bike will not seem to notice -- an ideal situation. A good illustration of this is when negotiating a series of esses (right / left / right, etcetera) at an elevated speed, or even the speed limit. The turns come at you very quickly and you will find yourself trying to move to the other side of the saddle while actually in the next turn -- a bad situation! I've found that the act of moving across the saddle can actually quicken the transition. Stay with me here. In a transition you are countersteering to stand the bike up from leaning through the previous turn, and as vertical comes and goes initiating the lean for the coming corner. If you are moving on the saddle at the same time you are decreasing the weight of the bike, and therefore the mass that is transitioning, and as you are getting to the desired position you can (at least I do) stop your motion by applying your weight to the tank / seat junction with the outside thigh, which will actually hasten the last part of the lean. It is at this point that smoothness is absolutely essential -- too much force can push the bike too far to the point of laying it down. This is an advanced technique that should be approached cautiously.
5 -- As you gain proficiency at hanging off you will notice precise control is augmented by subtle shifts in body position. Quite often I find myself having to make a slight correction in the path through a corner, especially on the street to avoid something, and a small adjustment of my body position will accomplish this without a lot of steering input. Remember earlier I said hanging off will make the bike tend to steer in that direction? Well, that's what you want in this case. To widen your line through a turn just lean your body a little further -- the bike will stand up a little and steer a little wider. It's all about the combined CG shifting.
6 -- Another advantage of hanging off is traction control. This is more useful on the track, but still applies for the street. Simply stated, if you feel the front end start to tuck in, indicating the beginning of a slide, moving your weight back slightly will unload the front and bring the tire back. the same can be said for the rear. Again, this is an advanced technique, and will come with practice and experience.
7 -- Hanging off augments feel. I've found that when I'm sitting square in the saddle the feel for what the bike is doing in a corner isn't what it should be. As an example, when I first started riding my 919, I thought the handling was, well, funny. Keep in mind I came off of 13 years of riding a Hawk GT, which is posessed of a hell for stout chassis, especially considering the relatively weak motor. Making the change to the 919 was a bit of a leap in the opposite direction -- lots of motor, flexible chassis, though not all that much heavier than the Hawk. I found that when I hung off the feedback from the center of the frame was quite a bit more readable: when the backbone deflected, the movement was really obvious, and I quickly found it was utterly predictable, with no winding and unwinding or sudden releases of stored energy even when sliding. It would have taken considerably longer to notice and quantify this feel if it was being attenuated by the seat foam. Hanging off gave a direct path from the outside peg to the rear of the tank through my leg, and it's relatively easy to read, that is if you know what to feel for, which I fortunately do. I can't explain what it feels like, but the feel is definitely there.
I've found that since I learned how to properly hang off a motorcycle it has given me a greater understanding of the bike / rider interface, and in consequence I'm a better and safer rider.
So be smooth, and practice practice practice.