Select Mission:
Goto the Main Menu and enter the following:
Select(x2), Circle(x2), L1(x2), Circle, L1(x2)

Full Health:
During gameplay press pause and enter the following:
Select(x2), Circle(x2), Up(x2), Down

50 Med Kits:
During gameplay press pause and enter the following:
Select(x2), Circle(x2), Triangle, Select

Instant Mission Completion:
During gameplay press pause and enter the following:
Select(x2), Circle(x2), Select, Circle

Access All Mission Weapons:
During gameplay press pause and enter the following:
Select(x2), Circle(x2), L1(x2), R1(x2)

Debug Mode:
During gameplay press pause and enter the following:
Select(x2), Circle(x2), L2, R2, L2.

X-Ray Vision:
During gameplay press pause and enter the following:
Select(x2), Circle(x2), Select(x2), Circle(x2)

Invincible:
During gameplay press pause and enter the following:
Select(x2), Circle(x2), Triangle, Select

Access All FMVs:
During gameplay press pause and enter the following:
Select(x2), Circle(x2), L1(x7)
Now goto the Options Screen and choose MOV