shaposhnikova:
Start on the low bar facing away from the highbar. Do a clear hip circle but release the low bar before completing it and swing up to the high bar.
Here's a video
[youtube]LjZEAQPgWPQ[/youtube]
It's the first skill of her bar routine--after the kip. This was her performing the skill, nowadays the bars are a lot farther apart.
As far as drills for the Shaposh I would say lots and lots of powerful clear hip circles, then progress from there. I'm not sure of the progressions because I've never seen anyone taught the skill, but I always wanted to learn it.
Tinsica:
Here's a video of an ok Tinsica, but hopefully it'll give you the idea. It's basically a front walkover where the gymnast puts their hands like they would for a cartwheel.
[youtube]7UeAiKcm1a8[/youtube]