At the main game screen, hold down [CTRL] and type in the code.
Code - Result:
hdilore - Research All Techs
hditech - Complete Current Research
hdirate - Add 100 to Mall Rating
hdicash - Add $100k to Cash
hdizooma - Unlimited Zoom
hdidizzy - Hold [ALT] and Press UP
hdiart - View Sim Animation Data
hdimax - Unknown Effect