I pinched this off another site.
Mike I know how it is to be bit by the bug and want to learn how to hack, so I will tell you how I learned, I will be as descriptive as possible, this technique I learned by tring it out in parking lots late at night at the local mall, you pick the best place for you.
First thing you want to do is to try it in a straight line.
Get the bike going reasonably fast (4th or 5th gear) with PLENTY of room to spare at the end of the parking lot or wherever you are, Now
WITHOUT allowing the bike to engine brake or decellerate pull the clutch in and downshift 2 gears quickly and just as quickly modulate the clutch (release it) to about half pull (there about) while "covering" the rear brake, (meaning apply just enough rear brake to work together with the clutch to brake the rear tire free.
Now the tricky part is in understanding what is really happening here, The bike is traveling at speed (X) and the rear wheel is rotating at a speed constant with speed (X). So when you downshift and cover the rear brake while the forward speed of the bike is still (X) the rear wheel rotation speed drops well below that (X) and breaks free and the result is a slide, up to the point where the bike slows down to the same speed relative to the rear wheel rotation, then the rear wheel comes back in line with the front.
In a straight line all you will really feel is the rear wheel dancing around a bit behind you but the first lesson is to get the tire/rear wheel to break free so that you can grasp the concept.
Once you have that down you can then move to the next lesson which involves counter steering in concert with all of the above principles. This is done exactly the same way and with the exact same approach however the idea is to slide the bike in as close the the apex of the turn as possible, that concept is really the hardest to perfect because you have to train your mind to go alot deeper into the corner prior to sliding or you UNDER shoot the corner and apex too soon.
Counter steering is an ABSOLUTE in my opinion when sliding on pavement for 2 very important reasons (1) you are physically PUSHING down (away from you) on the opposite grip which forces the bike to lean which then gets you onto the edge of the (rear) tire and (2) gets the front tire pointed into the direction of the slide.
The biggest mistake you can make here is to stay on top of the bike during this process, you need to get down into the "hole" with your upper body with the majority of your weight as low as you can get it while still maintaining absolute control of the bike. If it hooks up and you are on top the result could be a high side.
The only variable I can think of would be the number of gears you need to downshift in order to get YOUR bike slide at any given speed, also another note to make is to be very aware of chatter and hop during the slide, if the rear wheel starts hopping pull the clutch in slightly and back off the brake a little.
Take it easy at first and learn to get the rear wheel to break free in a straight line first.
I am assuming with all of this you will be trying this technique on a 4 stroke machine? 2 strokes are a lot harder to perfect due to the lack of engine braking.
The speed with which you "Dump/Modulate" the clutch will have a BIG impact on how this process works or doesnt work but youll figure it out.
I hope this has helped, and I hope you remember to keep the speed up when you get to the sliding into corners part, the slower you go the more tendancy there is for the bike to hook up and high side you. Have fun.