I'm making a republic star destroyer in the Rhino 3-D graphics program and i was wondering if there is anyway to put my model into and .odf file or some other file that would work for modding?

no the only program that has a .msh exporter is softimage|XSI and im unsure of milkshape modeling since its kinda a so-so modeling program.

Well, we can't say that Milkshape is a professional 3D-modelling software, but it knows handling many formats and it is very cheap...