Thanks for writing and for your question.
What you can do is basically extend the template of the control by adding a NOW
button in the popup. Then you should handle the Click
event of this button and set the Value property of the selector within the popup to DateTime.Now.
You probably will find useful taking a look at the PopupDefaultValue
property which allows you to specify a value for the popup without making it the selected value.
I hope this helps.
the Telerik team