I try to pitch cold, but closer to 52-55. It's difficult for me to get it all the way down to 45 F since my lager fridge is set to about 48 F. So I chill with the IC and then further chill in the carboy in the fridge, then pitch when it gets reasonably close to 48 F.
FWIW, It's allegedly better to propagate starters (even lagers) around room temp. There was a comment in the most recent Zymurgy mag (the article on dark lagers) that you need to let the starter sit at 60 F or less for a day before pitching cold. I only mention this so that if you do choose to do this you'll allow enough time for this 'rest'.