If your model is already made head attached, u can just select the head and if u select all the faces u want from the head just go detach. That will make it a seperate obejct from the body. then grab the head and make as many clones as u need for smile/angry etc. After u have made all ur morphs and are happy.. Simply select ur original head and reattach it to the body. Ur stack will look like this From top to bottom:
meshsmooth (if wanted)
skin
edit poly/mesh
morpher
edit poly/mesh
The bottom one will be ur head alone (edit poly) with the morpher on the top, then attach the body/head back together above the morpher, then put ur skin on if uve got the bones for the rest and need to make ur envelopes etc.
Hope that helps.
Other people may have a better way of doing it tho, just see what kind of ideas u get from others i guess

and how it all works for u.