Adjusting hilt size and position should be covered in the saber making tutorials. Be aware though that, in my experience at least, radical repositioning of the hilt (both of the model itself and the pivot) in GMax is inconsistent at best. Be prepared to re-export the model multiple
times to get the result you are after.
Also, make sure you are using v0.5 of MDLOps. Get it here
. The newer version hosted here at LucasForums doesn't play nice with sabers. I also found that v0.7 of NWMax worked better than the newer v0.8, at least in GMax.