I did a snowboard trampoline class at Acrosports (a circus acrobat school) in San Francisco, we did it on an Olympic trampoline (i.e. big and powerful) - it apparently isn't offered anymore. Woodward at Copper (skateboard/snowboard training facility) has trampoline training as well - maybe you can ask them.
Just visited the website, it looks so cool! I wanna go now. I don't think we have anything like this in the UK, but I'll be on the phone first thing in the morning to fin out. I'll also contact Woodwards to see what they offer. Cheers for the lead.