It appears that hp_active seems to be the default point at which the character grips the weapon. I was wondering if there was a way to change that, so that he/she gripped it at a different point (the point I had in mind already exists on the model, it's just not hp_active). Is there a way to do this while avoiding using XSI?

So long as it's still a hardpoint you just need to reference that in the odf

Cool! But what is the ODF paramiter for that?