During gamplay, press CTRL+12. Enter these codes at the prompt.

Note: they will not work in Campaign Mode.

PILE IT ON - Add resources
Q40 - Research everything
GREEBLIE - Complete research on the current project
WALL2WALL - Max population
LEO - Show resources/military units in enemy territories
BIGBRO - View any territory
CHARISMA - Be friends with all computer players
S-MART - Skirineen appears immediately
SQUISH - Win scenario

HeXCheat:

Edit (with a hex editor) the file DL2.PRF and go
to offset 117 (0x75) and change the value of it
to 7F. This will give you the ability to view the
Campaign Cinematics at the campaign race selection screen.