Strong bridge with a tight flexed body, looking at your hands.
Neck kips (floor kips).
Floor Kip to Bridge.
Back extrension roll to bridge.
Back extension roll up a wedge, to bridge, to stand.
Get yourself a tumble track, learn back bounces to handstands.
From there, basically do a backbounce to bridge on the bar. When you can do that, put some padding where your ankles may hit on the bar, and bridge on bar, stand up, fall back to support over the bar. From there, speed up the process until you pop over the bar and do a tkachev on the tramp bar.
If you would like, an alternative is to not use the bar, but the end of the tumble track, and make yourself travel backwards into a porta-pit that is level with the tumble track.
To help with the turn-over, a solid pancake position will help a ton! Thout it is not necessary.
I cant think of too many other drills at the moment.. Im sure a few more will pop up...