See my answer to a similar question I asked. Basically one option (that worked well for me) is to implement your own collision listener into Bullet Physics. All you really need to start is a function of your own that tells you whether a specific point in your world is solid. Then as you can see in my answer, you'll just need to override a few objects, and you're done. Most of the code can be copied from the original terrain collision listener, then slightly modified for your game. This is a fairly powerful way to get collision handling working, but it might not be the simplest.

See my answer to a similar question I asked. Basically one option (that worked well for me) is to implement your own collision listener into Bullet Physics. All you really need to start is a function of your own that tells you whether a specific point in your world is solid. Then as you can see in my answer, you'll just need to override a few objects, and you're done. Most of the code can be copied from the original terrain collision listener, then slightly modified for your game. This is a fairly powerful way to get collision handling working, but it might not be the simplest.