1. Press CTRL+SHIFT+C to bring up the debug console
2. Type boolProp testingCheatsEnabled true and press enter
3. Hold down the SHIFT key on your keyboard and at the same time click the left mouse button on a sim. You will be presented with several new menu items/cheats/etc. There's lots of goodies in the testing cheats - so poke around and experiment. Not everything in the menus work, however - but most do.
Thank's work' know.