I have the genital prop from here http://www.sharecg.com/v/42779/browse/5/3D-Model/A-new-genital-prop-for-V4-A4-G4-S4-L3

I want to use it on my g2 jessi figure. But I have a problem. I don't know how to get it attatched in the right spot and when it seems I do it looks...well...like a prop and not part of the body.

Any thoughts on how to do this?