I usually edit using trail and error with notepad, just a sample here of a custom hardpoint edit.
[HARDPOINTS] ;; -left/right+, +up/down-, +forward/aft-
mount.0=2.43,-0.70,1.03 ;start of cannons
mount.1=-2.43,-0.70,1.03
mount.2=2.88,-0.63,0.90
mount.3=-2.88,-0.63,0.90 ;end of cannons
mount.4=0.805,-0.80,0 ;inner wing pylon right
mount.5=0.805,-0.80,0 ;inner wing weapon right
mount.6=-0.805,-0.80,0 ;inner wing pylon left
mount.7=-0.805,-0.80,0 ;inner wing weapon left
mount.8=3.800,-0.788,-0.10 ;rocket pylon 4 right
mount.9=3.800,-0.734,-0.10
mount.10=-3.800,-0.788,-0.10 ;rocket pylon 4 left
mount.11=-3.800,-0.734,-0.10 ;rocket 4
mount.12=3.383,-0.868,-0.10 ;pylon 3
mount.13=3.383,-0.814,-0.10
mount.14=-3.383,-0.868,-0.10 ;pylon 3
mount.15=-3.383,-0.814,-0.10
mount.16=2.966,-0.948,-0.10 ;pylon 2
mount.17=2.966,-0.894,-0.10
mount.18=-2.966,-0.948,-0.10 ;pylon 2
mount.19=-2.966,-0.894,-0.10
mount.20=2.549,-1.028,-0.10 ;rocket pylon 1
mount.21=2.549,-0.974,-0.10 ;1st rocket
mount.22=-2.549,-1.028,-0.10 ;rocket pylon 1
mount.23=-2.549,-0.974,-0.10 ;1st rocket