Short Answer: No
Medium Answer: Yes, but the AI won't use it, it'll only fire forward, and it won't work with beams.
Long Answer: Yes. You can simply just set them up like fighter primary/secondary firepoints, but there will be issues including capital ship AI not using them, them being fixed forward unless you use a special table flag to fire down normals and even then they can only fire down exactly where they are pointing, and don't play particularly well with beam weapons. This way you can get weapon points that fire when the player pulls the trigger (it's how they get the player-controlled guns working in Blue Planet War in Heaven's Gef Asteroid base capiship command mission), but outside of that role of fixed forward guns for a player-controlled ship there is very little practical use. There are ways to work around this and make working gunpoints on the hull, but they'll be hackish. The most straightforward workaround would be to copy a single-part turret (any one will do) in PCS2, embed it in the hull (move it so it its completely hidden), and set the fire point to be where you want, also in PCS2. Then add the appropriate turret subsystem in the table and set it to "untargetable". Why you want the ship emitting weapons from...the flat side of the hull without the possibility of interacting with it is beyond me, though but it can be done. I guess I can see this if you're using a custom model that has a bunch of casemate guns built into the hull recessed in armor and you don't want them to be able to be disabled like other singlepart turrets because they are very well protected or something.
Unless of course, by "hardpoint" you mean single-part turrets and by "turrets" you mean the rotating barreled turrets. In which case ignore everything above. Adding one is trivial.
- Copy, paste, input new coordinates for where the singlepart is to sit, give it a new name in PCS2.
- Copy a turret subsystem entry in the table, change it to refer to the new name.
- ???
- Profit
Can literally be done in a minute or less.
This is whole process is exactly what I mentioned in the hackish solution to get beams/lasers firing out of anywhere as explained in the long answer, except that you'd be placing the singlepart turret (the physical model/collision box) wherever you want it to be on the hull instead of hiding it inside and only moving the firing point (where the actual projectile comes out of)
