To court Millie (she's a strange girl), you'll always want to show up at her house at 14:00 wearing the gimp suit.
You'll need to wine n' dine Millie in order to wheedle the keycard out of her. It will tell you that the mission is complete, and you will read that the gimp suit has been delivered to your wardrobe. When it concludes, Millie will be your new girlfriend. Step in the red marker to see the lurid cut scene. Kill him before he arrives and pick up what he's holding.
Get out of the car and look for a dude holding a big purple dildo moving toward her house. She goes inside, but you have to wait for the master. Again, don't get too close! The croupier will take the same sort of lazy route through the city, but eventually she'll reach her neighborhood. Once you're in it, run outside and get back in your ride.
Go into the dressing room nearby and get into the Gimp Suit.
