So with the newest add-on's, you can add hp's to the model with using the joint tool and labeling them hpXX and so on. Well, i've set all of my hp's using joints and labeled them all correctly, then I goto export the mesh into the A2 sod file, and here's where it gets odd.. The file size of the completed sod is 1.82k and that was my first red flag... Then I bring the sod file into AssimView and all that shows is the hardpoints, but no model. Then when I export the sod without hardpoints, the model will show in assimview.
go and get majorPayne's hardpoint tutorial for milkshape, it's around here somewhere i found it, check the usual download sites, i'm not exactly sure where i got it, but anyway, it includes how to work out a heirarchy for the hardpoints, which is very important, also mesh points as well, so you should check that out, it helped me, to a point