Silverlight™ and WPF do not include core DateTimePicker controls to be directly usable in CellEditTemplate definitions accepted by the DataGrid based components released by DlhSoft.
However, you can the DatePicker control which allows selecting a date and then manually entering the time of day in the textbox, separated by a space. Moreover, we have a FinishDateConverter that may be used to select finish dates and automatically consider the end time of the selected day.
Alternatively, you can use the DateTimePicker control from WPF Extended Toolkit, another third party date-time picker components, or the WPF based DateTimePicker control developed by DlhSoft and available within the common DlhSoft.Data.Controls library borrowed from previous WPF products (this component doesn't require a separate license).