Security skins:
Complete the King's Ransom level on 
the "Secret Agent" difficulty setting 
with a time less than 3:45 to unlock 
the Security skins.

Soldier skins:
Complete the Midnight Departure level 
on the "Agent" difficulty setting with 
a time less than 3:05 to unlock the 
Soldier skins.

Suit skins:
Complete the Curiour level on the 
"Secret Agent" difficulty setting with 
a time less than 2:00 to unlock the 
Suit skins.

Scientist skins:
Cmplete the Masquerade level on the 
"00 Agent" difficulty setting with a 
time less than 4:20 to unlock the
Scientist skins.