Ultimately, you'll need to convert the model again before you can make a HL model, then you need to compile it.
I recommend blender, it's free and has plugins for Half life. So find a format you can export from solidworks, and import into blender. Then you'll need to add a single bone for a static model, or multiple bones and an animation for a dynamic (animated) model. Export that file to a .smd, and create a qc script to compile the model.
It's a pain to figure out for the first time, but once you get the workflow down, it's not too hard.
If you need help along the way, just ask.