Originally Posted by jock
As for sizing I haven't got a clue until I see you on it. The geometry is diff to a road bike because the BB is a little higher and the seatpost tube is (generally) at a steeper angle. Go with what climbo's advice, or Thylo if he offers any. You will need to match your reach though. Start with the top-tube length the same length as your road bike, and adjust stem length, angle and height to suit your sprint position. Your BB (centre) to top-of-saddle measurment should also be similar to that of your road bike (irrespective of the seat-tube post size), maybe just a smidge lower if the seat is positioned a lot further forward than on your roady.
Now now, don't be like that. I offer free advice all the time....whether people want it or not!
So yeah, exactly what jock said!
Oh, except if you sit further forward, generally I reckon your seat needs to go up rather than down, because when you sit forward it encourages you to pedal less heal down and also makes it less possible to sit rearward in the saddle, reducing the effective saddle to BB height.
As to track specific advice, I can't really help. Never ridden track in my life. However, as long as you keep your hands, butt, and feet in the same position relative position, I can't see how you can go too far wrong.