Or just bring up the cheat console and enter "sethour X" where the hour is in simplified military time. (1 for 1:00 am, 13 for 1:00 pm, 19 for 7 pm). No need to get a kitten-or-puppy killer.
Thanks, didn't know about that cheat. That probably will work better than InSim anyway, which is very twitchy when changing times. You don't always get the time you expect.