I am modeling a handle and am using the Freeform tool to create a contoured surface for finger grips.  When I place the curve on my surface to be deformed, however, I can't get it placed exactly in the middle of the surface.

1. Is there a way to constrain a curve in the Freeform tool so that it is centered about a given face?

2. Is this even the best way to do what I'm attempting?  Is there a better way?

The attached screen shots should give you an idea of what I'm trying to do and the problem I'm encountering.

Thanks!