@ksanderson: The SetUp room can't handle V4.2's multiple ERC layers, so just save the 17kLOD object somewhere in your runtime and edit a V4.2 cr2 to point to it.
No need to rename bodyparts or groups as they are named exactly the same.
No need to edit the rigging as V4.2 and the Lod are shaped EXACTLY the same.

The original V4 morphs won't work anymore of course, so you have to delete them, either with a cr2 editor or MorphManager.
Then resave that "empty" cr2 to a folder in your runtime.

Then let the Cage/Spanki script analyze V4.2 and the Lod geometries, inject the morphs you want transferred into V4.2, and then transfer them over to the empty Lod cr2.

If you want the fully automatic functionality of the original V4.2  you'd also have to transfer/convert the various JCM morphs and put them into th exact same position as they were in the original V4.2 (with the exact name), so that the ERC will still work.

Given how complex V4.2's cr2 is, that can be pretty complicated and error prone.

Instead I simply deleted all the JCM morphs as well as all the JSM magnets, and just added a few morphbrush morphs to fix the joints where necessary.
A lot simpler, a lot more efficient, and a lot more flexible than the original rig.