I can't seem to find the original post/article where I read it but, Todd Adams had custom springs made for his lift.
I assume that the same company that made the custom springs for his lift could also make custom springs to lower the thing.
I think they were called springworks or something like that. You should email him (he doesn't visit here much unless it is getting close to ZuZoo) and ask.

Of course my memory may be completely failing me, and it could have been someone else entirely.