By donning a mind-control helmet (only usable at certain points in each level), you'll be able to take control of Stewie's mom, Lois. The microwave by the door disrupts the mind-control signals, though, so you'll have to take the more indirect approach of forcing Lois to chase Brian outside with a vacuum cleaner.
Above: Screens shown here are from the Playstation 2 and Xbox versions of the game.
In the following hospital level (which traded in a lot of the platform-hopping for hard-to-control swimming through rivers of liposuction fat), we got to use the helmet to take over aggro pervert Len Quagmire and scare a few nurses toward waiting laser beams. Not even Death was immune; after getting him to show up by unplugging a few life-support patients, we hijacked his bony ass and had him take down the nurses guarding Peter's hospital bed. All this, just so Stewie could shrink down and ransack Bertram's abandoned base. The one he used when he was just a sperm cell.
Sound nasty? That's nothing. The 'M' rating gives the writing staff a lot more freedom than TV does, and they're apparently determined to work it for all it's worth.