You don’t need to adjust it to fit in a modeler - if you own the V4 and/or M4 shapes for Genesis.
Load V4 (or M4), and zero the figure.
Load genesis, dial in the matching morph.
Pose Genesis to match the zero pose on the Gen4 figure. You will probably want to save this pose for future reference if you think you might do this again. I mean, why not?
Apply clothing to Genesis. It conforms, Genesis applies the Gen4 shape, and now if you export it out as an OBJ, it is ready to be rigged for the Gen4 figure.
Not that rigging is particularly a joy or anything :D But either way you’ll have the shape done for you.