How can I adjust the apparent color temperature of my display in OS X? I really like f.lux, which is an app that automatically adjusts the display's apparent color temperature according to the time of day and location (so that the temperature is in sync with Sun).

How to set the color temperature manually? I.e. without f.lux? 

Sometimes I'd like to have "tungsten" (2700 K) colors during the day or morning, which would require fiddling with the location coordinates in f.lux. Sadly, there's no "manual mode" that I'm aware of.

I'm looking for a OS X native / software based solution, that would allow me to set white point below 4500 °K, which is the minimum that Color Calibrator can set. Is this even possible?
When using the Displays section of your System Preferences, if you calibrate it, select show advanced options, one of the windows is this:
 which to me looks like the white points you were looking for, be sure to uncheck "Use native white point" if you want to manually edit it.