HI
 I am doing something simple,  I am making a pair of skin tight pants for a figure...i figured rather than define a bunch of material zones every time I want tights, or skintight pants on the figure I  could just join together all of the desired  polygon  groups  as a conforming prop.  and whenever I feel like throwing these skin tight pants on a figure, boom i just load the conforming pants from prop library  - i grouped polygons of the hips and legs and saved all of  these groups as props - I can join them  (thru the export/ import method ) , into one prop " pants"

BUt my problem is I don't know where in the process, and how, do I make it  a conforming prop for that figure

so that it conforms  and moves with the figure

If you really just want a skin-tight look, a material is going to be immensely easier.  If you are dead set on learning to rig conforming clothing, be aware it's about the hardest thing you can approach in Poser - not that you can't learn it, just don't think it's simple.  I encourage you to watch Phil Cooke's video tutorials on rigging in Poser:

http://www.philc.net/tutorialsIndex.htm

Rigging conforming clothing for an existing figure is somewhat simpler, but it relies on many of the same techniques.  You're also going to need to learn how to design and implement Joint Controlled Morphs (JCMs) for areas like the knee; these are present in all of the more advanced character figures, and need to be replicated somehow into any tight-fitting conforming clothing.

http://www.nerd3d.com/modules.php?name=Content&pa=showpage&pid=8
http://www.rbtwhiz.com/rbtwhiz_ERC.html

Thank you for that advice -
I will get into rigging later

can you tell me - how do I save a bunch of material zones  so that when I start new Poser scenes,  I can load the same figure that I made the mat zone for previously ...and I can find the material zones from before - already made.

If you are applying these material zones to a character figure, just re-save the figure to the Characters library under a new name and the material zones will be included. 

yeah good point - 
I never save my characters  cuz  I feel  like they are never  done!

so it did not occur to me.

I will save the base figure with the zones

Thanks

Rather than creating JCM's an alternative is to just hide the body parts through a material mask. Since more than likely that the offending body part is underneath your clothing...really don't need to see it, if you don't see it...it doesn't poke through.

Or...you can labor away like pjz.

Well, JCMs are there for a reason - if you don't add it in places like the knee, then even if you hide the character's knee, you will often get a very "pipe like" bend.  Better to just texture the character's own polygons and show the JCM than cover it up with PVC pipe.

So removing the JCM of V4's buttock and replacing with a custom JCM could be a way to  "redesign" that ugly bend that gives her a donut butt?

Maybe :)