The easiest way to edit your warehouse inventory is to start a new game and save straight away. Then do the following....

1. Go to C:\Users\#YourUsername\AppData\Roaming\Carrier Command 2\saved_games\
2. Find the correct folder (will be the latest one)
3. Edit the XML file
4. Search for team_control="1" this should locate your starting island XML data
5. Scroll down till you find the inventory tag and below that will be a list of quantities that looks like <q i="0" q="0"/>
6. Either edit or add extra lines. So if you wanted 8 Mantas you'd add the following line
<q i="5" q="8"/>

Small Munitions
31 : Flare
32 : 20mm
33 : 100mm
34 : 120mm
35 : 160mm
45 : Sonic Pulse
46 : Smoke
48 : 40mm
0 : 30mm

Large Munitions
14 : Light Bomb
15 : Medium Bomb
16 : Heavy Bomb
17 : IR Missile
18 : Laser Missile
19 : AA Missile
29 : Cruise Missile
30 : Rocket
37 : Torpedo
38 : TV Missile
39 : Torpedo (Noise Maker)
40 : Torpedo (Countermeasure)

Turrets
9 : 30mm Turret
10 : Aircraft Chaingun
11 : Rocket Pod
12 : CIWS Turret
13 : IR Missile Turret
26 : Flare Launcher
27 : Battle Cannon
28 : Artillery Gun
47 : 40mm Turret
49 : Heavy Cannon

Utility
20 : Observation Camera
22 : Gimbal Camera
23 : Actuated Camera
24 : RADAR (AWACS)
25 : Fuel Tank (Aircraft)
41 : RADAR
42 : Sonic Pulse Generator
43 : Smoke Launcher (Stream)
44 : Smoke Launcher (Explosive)
50 : Virus Module

Surface Chassis
1 : Seal
2 : Walrus
3 : Bear

Air Chassis
4 : Albatross
5 : Manta
6 : Razorbill
7 : Petrel

Misc
36 : Fuel