[ODE] A beginner question about applying forces on a body

[martin maximilien]

Hi,
I want to apply a set of forces,  on a sphere, with friction at the 
contact points of each force.
My sphere has a translation and rotation parameters, and is rotating on 
a plane, with another friction coefficient.
How can i modelize all that ?
Apparently, dBodySetForce is operating on the mass center, or am i wrong ?
Tx for your help.