But going back to real trackstanding business, I think that the ability is underrated. It seldom gets used, but it's a good tool to have. I've benefitted from the ability numerous times. Without a track nearby, I learned by finding progressive slopes where it was convenient to practice. I first started on a quiet side street using the slope provided by the crown of the road. First on the right side, then on the left side to mimic the track slope. I then went to getting myself sideways on sloping driveways. Ramps that lead into underground parking lots were next. Make sure that you can pull/skip your back wheel up the bank to get yourself pointing down the slope. You control your roll forward/back with the front wheel and back pressure on the left pedal. Turn your front wheel up the track and it will help you roll backwards you'll roll backwards.
https://www.youtube.com/watch?v=1817Jxl1ve0
With the right bike/front wheel angle, you only need moderate back pressure to stay in one spot. You'll know you have the right balance when you're weight is on the back leg, but barely. You should feel as if you could hold it all day. You want your right leg forward as it will help you shoot down the bank when you accelerate on that first stroke. You'll see this set up in all the top sprinter's track stands. You'll also see the exact opposite when they do standing starts because left foot forward helps to keep you straight/up the track.