I am assuming that you would be shooting in RAW format (and you could still adjust the white balance to a degree in JPG), but you can set the white balance on the Pentax K10 before shooting very easily, or if you forget, adjust it in post processing.
You can set the White Balance on virtually any popular camera now, and on a DSLR model, you usually have presets for Sunny, Flash, Cloudy, Tungsten, Flourescent, Kelvin Temperature and Custom (so that you can use a Photographic Gray card or white card to set it in the light you're shooting in).
You can also change the white balance in post processing if you shoot raw with any of the cameras being discussed. Most raw converters will use either the "as shot" white balance (applying the rgb muiltipliers the camera stored in the metadata during raw conversion for the way it's WB was set), or allow you to change it to something else if desired. That's not unique to Pentax.