Currently this is not possible with this version of RadDateTimePicker
as the editing text box is disabled. Changing its fore color doesn't affect its appearance.
This control is currently part of RadCalendar
, but it will be officially released as a stand alone control in Q3 of RadControls for WinForms. With the Q3 release we will provide masked edit functionality as well, and then you will be able to change the fore color of the text box as it would be editable.
If you need more assistance please write back.
the Telerik team