oh!  yes, Cr2 Editor is free.  it's actually kind of an old prorgam, and i think there are more robust but commercial applications that do the same thing.  and i'm pretty sure that you need a version before the last one because the version after it messes up the cr2 files it saves.  i think you want version 1.5 vs. 1.6. 

probably the best place to get it is English Bob's listing of utilities.  http://www.morphography.uk.vu/dlutility.html

i really don't know enough about the process  Zbrush needs or precisely what you want to do to give you much more specific information.  i know in Blender how to select faces and give them a new material zone, but i have no clue how to do it in Zbrush.  and i never got good at creating hybrids, because i never could get the Poser grouping tool to work across groups. 

which previous morphs?  yours or the MFD's?  so if it's the original MFD morphs, that's the point of just changing the obj file the cr2 is pointing at (and saving as a new .cr2 - never overwrite your original file).  it has all the same properties as the old figure but with an altered source.  so as long as you know how to make morph targets in Zbrush, it shouldn't be a problem.  basically, you keep the vertex count and order straight, and you're good to go.  if it's your own morphs you make in Zbrush, then the point of this excercise is that you can make any change in Zbrush you want to the obj that doesn't affect vertex count or order, export the new object, and use it as the source for your new cr2.  morph it, add material zones, even remap it as you please.

when i first started following this thread i was really into the idea of hybrids.  now i don't have much use for conforming clothes at all.  maybe i'll have learned so much about dynamic clothes in a year or three that i'll have hit their limitations, but right now there's just no benefit to conforming clothes for me.  i've barely begun to understand how dynamic clothes really work.  i mean, there's definitely features i wish i could request for Poser 9.  but there's just so much i haven't really tried, and so much that's generally seen as a difficulty when in actuality it's simply a limit of cloth.    so i can't really advise you on working with hybrids because i can use them well enough but have only theoretical knowledge about making them.