You interrogate the DateTimePicker control like any other. You drag the bullseye on top and it is added to the hierarchy. If the control is not recognized as that type and is instead a generic control, you would likely need to work with support to determine if a translator is needed to operate on the control.
Being it is an Infragistics control Pega Robotics most likely will not work with it unless a translator is created. Currently translators are created by the Pega Robotics engineering group.
With that said I have seen some DataPicker controls that update a hidden input in the HTML. If the DatePicker control does update a hidden input you might be able to update the input directly without using the DatePicker control. The IE Developer Tools (F12) can help you find controls in an HTML page.