You can group your mesh in your modeller, in a UVmapper like UVmapper Pro, or in Poser itself. 

All of them take practice.

Just remember, Poser has some very strict internal namings that are case sensetive.  Deviating from these can give interesting results.

The best reference for this type of Poser rigging is still

The Secrets of Figure Creation in Poser 5 by BL Render.

If you want your poduct to be useable in the most versions of Poser, do not use the newer encapsulated joint rigging introduced in P8.  It does improve bending in some figures but is only useable in P8 and up and doesn't really work in DS.