A'ight, it seems that after I use the morph brush to fit the pants to the M4 with the M4 Enhanced Svelte morph, I can select "Save a copy as" and name that to Svelte and just delete the "Custom Morph" after I finished.  

A secondary around step but I think I understand what you were going for here.  If I just do the morph brush and close it, I can click on the parameter dial named "Custom Morph" and change the name there instead of duplicating it as I stated before.

Alright then!  When I'm finished, I'll check the CR2 and make sure that it's listed there as well.

 

Edit: It is there, as is a .pmd (primary morph dial) line above the .obj line which I haven't seen before.  

I've gotten the Svelte and the Prosaic morphs in, but it won't even let me use the morph brush for the Spartan (the third morph of the four).  I use the brush as the turorial stated, exactly, and nothing morphs on the pants to match M4's body that has the Spartan morph set to 1.  Argh.