magnets are your best route for doing this from within Poser. 

Other wise what your looking to do is Model the Face, for wich you will need a Modeler application, wich Poser is not.

There are several free modeler programs around, though I do'nt know how to use any so I wo'nt name names.  The Modeler most closly related to Poser is named Carrara 5, and itt's available at Daz3D.com.  But, do'nt scuff at it's price untill you've seen what it's big brothers' 3D Studio Max, Lightwave, and Maya go for!

This all kinda put's Poser Magnets right back into perspective, allthough there is a nack, a Modeler has, that is a bit different.