[ODE] Collision CSG?

[gl]

I have been looking at a number of 3D models I've designed recently - very
detailed large ones which may, for example, have players jumping and walking
on them and which will move themselves - and it looks like getting good
smooth collision response on some of them with primitives only will be hard.
I'm sure it can be done by using lots of small prims to pad out the empty
spaces left by the larges ones, but getting smooth transitions between them
won't be that easy, and they may still not approximate the mesh shape well
enough.

I wondered for a while whether it's possible to do something akin to CSG
with collision primitives - that would be really handy.  For example,
imagine a hollow glass sphere that has small objects inside it.  If you
could use a collision sphere, and then subtract a smaller collision sphere
from it, you could do this with just two primitives.  I don't know if this
is feasible though (contact generation might be hard) - any thoughts?
--
gl