In some ways "tipping board" is a misnomer. It's not really for learning how to tip as much as how to balance while tipping. A tipping board presents a challenge: can you tip upside down to the hill and stay in balance and control. I have a video on my website named: Getting upside down to the hill: Balance for carving the top of the turn." It shows a dryland exercise on a sloped driveway. So, yoiu don't have to build a tipping board, but it works there also. The video was in the registered user section of my site, but I just moved it to the public area because of the discussion in this thread. Check it out if you want.
http://skiersynergy.com/blog
There are a couple of other videos of dryland exercises in the registerd section. One is on flexing while maintaining forward pressure and another is on flexingf to release. Feel free to register and check those out also. I have several new topics that wil be published to the site soon.
Enjoy.