Sure. It's not complicated as it seems, but I did come across some odd behaviors.
First, you'll need to calculate the char's direction to center of the sphere which becomes new gravity and apply:
body->SetGravityOverride(dirToCenterOfSphere * 9.81f);
every frame. The
dirToCenterOfSphere * -1.0f
becomes char's normal, and from this you can derive the forward and right vectors which then provide the orientation for the character, i.e. Quaternion(right, up, forward).
Some odd behaviors that I'm seeing are that if you use inertia bounding box derived from a capsule, physics wants to pull the body back up to the top (like a magnet) ,and second is that there seems to be some odd acceleration going on when the char is 1/4 and 3/4 way down the sphere, something I'm still trying to figure out.
*edit: err, I shouldn't say acceleration at 1/4 and 3/4 because char doesn't move if I stop moving. It's more like no braking is applied at those areas.