There is a third party tool I found recently, a DIM zip maker.  I had some non-Daz3d products I got and used the DIM maker to make an IM file, and I tried 4 times, 3 worked (and I think I messed up the fourth, havn't tinkered with it yet)

 

DIM is nice because if you have too much stuff, you can add/remove it back and forth without problem, and it manages what's in the CMS for you.