I agree that the figure should be zeroed and you shouldn't have any problems making clothing for it.  However, Poser shifts the figure (cr2) ever so slightly from the position of it's obj file.  Because of this, I always use the original obj file to build clothes around.  If you load a zeroed figure, and then load it's obj file, you'll see that they don't match exactly.  I'm sure there must be a good explanation for this, but I probably wouldn't understand it if they told me.