Abandoned? 

Now that the Homeworld license has been bought by GEARBOX, I think we should rehype this mod. I'm thinking that the sins mod may be better than whatever gearbox is intending to put out...lol

Export obj files from the HOD editor.

Fix in 3ds max or whatever.

Convert to sins as normal.

I personally use milkshape for fixing the models, then convert it into XSI to add mesh points and tangents. Then you use convertxsi tool to convert the .xsi into .mesh.

If you have even a basic grasp of 3d modeling (which is pretty much what I have) then it really isn't hard.
I was going to make a Homeworld mod myself but since someone had already made the entrenchment one I decided to go with Freelancer =P

The one thing to keep in mind, is Sins does not have true turrets. So you have to decide which direction the guns are going to be facing.