WARP

1/ Do a nurbs head and do Ploygons->Nrbs to Polyg

2/Duplicate this polygonal head and move it along the object

3/Select nurbsface and poly1

4/ Deform->CreateWarp

5/Connect in mesh and outmesh of two polyfaces :

connectAttr -f nurbsToPoly2.outMesh nurbsToPoly1.inMesh ;

8/Hyde the polyface wich is under the nurbs face

9/it's intersting to turn the polyface whitout move the original, and move only vertex to modify the nurbs face