The distances are in feet, from the center of the model, usually 1/3 of the distance, from the front, of the wing root chord where it meets the center line (nose to tail) of the fuselage. I don't actually know the distance from that point to where the weapons actually go, but for a good idea, check out the location of the LeftTip fuel tank:

LeftTip   =  -35.3, -5.5, 1.0,  85, 0.0   ;Left Wing  //Longitudinal (feet), Lateral (feet), Vertical (feet), Usable(gallons), Unusable (gallons)
Ignore the red text as that is referring to gallons (tank capacity) and the unusable amount of fuel.

So if you place a rocket there, it will, most likely, be inside the wing. You will need to drop it down a bit. I just don't know how much.

One thing you need to be aware of is that if you give it the armament weight, after expending all your ammo, you will need to remove the weight from the aircraft after you are done. Oh the fun and games! ;D

Mark