Let's clarify morphing.  The exporting process of any particular body or prop part involves preparing it for morph targeting.  Once you import it into a 3rd party program and modify the mesh structure without disrupting vertices, you load your object as a morph target. 

I have used Argile with good results and with a minimum of fuss.  Have never worried about rescaling and never encountered verts disruption.

Or you could use Poser's native morphing tool.  It has improved significantly in PoserPro 2010.