How do I add vehicle hard points and get them working?

Thanks

I assume you are talking about on a model you are creating.
Just create nulls, move them to the positions where they should be, obviously hardpoints for weapons near the end of the barrel, but damage hardpoints would be where you'd like smoke and flames to appear as you vehicle gets broke.

One you have them in position rename them to what they should be, standard ones are:
hp_fire, hp_fire1 ..... etc
hp_damage, hp_damage1 .... etc
hp_aimer
hp_pilot (postion of the unit within the vehicle)

The most important thing to remember is DO NOT FREEZE TRANSFORMS on these nulls as it will set them all back to 0,0,0 and all your hard work will go for naught.