Once players in Wasteland 3 have completed the quest 'Cornered Rats' they will find that a lootable crate has been delivered to Ranger HQ, outside of the base structure, near the transition waypoint that leads to Downtown Colorado Springs.
Once the outfits have been looted, players will be able to suit their team up with the costume components within the wardrobe at Ranger HQ, or at the clothing shop in Downtown Colorado Springs.
Please note: if a character has an article of clothing/armor on in the slot where the costume has been added, that armor piece will need to have the visibility toggled off in order for the underlying costume item to display.