UK Helicopters - Self protection weapons missing - how to correct?

[IanH]

Hiya all, 1st post! I've been playing since the original DOS game and only recently found this version which has blown me away, however I've a question about the UK's transport helicopters which all lack any self protection weapons (except SF chinook). I'm in the RAF and work on Merlin MK3's/MK3A's so I know whats currently fitted to actual aircraft on operations and want to modify the game files but don't know how to (or if it's possible). Here's a quick list of what I want to add:

Army/Marines Lynx - 1x 7.62 GPMG
Puma - 2x GPMG
Sea King - 1x GPMG
Merlin Mk3 - 3x GPMG
Chinook (inc SF) - 2x 7.62 Miniguns & 1x M60

Any help will be gratefully received!