How to differentiate between Touch and Pen input from within DynamicRenderer?

See more:

C#

WPF

I am working on a windows 8 application using visual studio 2010 (limited to Net 4.0). I am using a custom InkCanvas with a custom DynamicRenderer. I would like to differentiate between the user touching the screen versus pen writing within the custom DynamicRenderer.

Just guessing, but it seems that I should be able to tell the difference immediately within

OnStylusDown(RawStylusInput rawStylusInput) {}

but all I can get to is a StylusDeviceID or TabletDeviceID when I think I need something on the order of a contextID of some kind.

I am sure there is a way...but I can't seem to find it.

Thanks for any suggestions!