I think he/she was looking for a tutorial to convert the skintones from a normal Maxis body shape to a custom body shape. I.E. Maxis to Athletic using one set of skintones.
Tutorials:
Skintones Linked to Marvine-Beosboxboy's MeshesThis tutorial seemed to be the easiest to use. This is an example of how a skintone can be either converted or linked to a different body shape.
Sims 2 Tutorials: Body Shop MeshingThis is a starting point for you to find tutorials to do what you wanted to do.