Robotech: Invasion Cheats

There are 2 ways to get the 3rd ending (Locke Ending):

THE HARD WAY:
- During the fight between Locke and the RCB (Royal Command Battloid; unique heavily armed Invid unit) at the Hive, switch to THERMAL vision and target her right shoulder. This is her only weak point. Destroy it if you can. Very difficult as the RCB is constantly moving AND shooting!

THE EASY WAY:
- During Tasha mission, after fighting past Hive defenses there will be a cutscene as Xed appears between Tasha and Locke. Aim your weapon at Xed (turn right, he is the guy in the middle) and fire. SHOOT XED QUICKLY and if done correctly, Tasha will get shot by Xed and drop the Destabilizer. Locke will then pick up the weapon and you continue on as him.

(thanks to Hunblood111 for helping me out)