Wacom function curiosity

[LGLA]

Hello all, need help on a small issue with my Wacom intuos (1) 6x8 tablet,
if anyone could?

I was reading a tutorial by Cher T. Pendarvis on how to set up a tablet for
use with PainterX:

"Customizing a Wacom tablet key to control brushstroke"
http://www.corel.com/servlet/Satellite/us/en/Content/1181934056653?trkid=tpc0607wow

This I would like to know for the Intuos1, if anyone could share which
keystroke it might be? That way it could be programmed in. The point
is to lose pressure sensitivity anytime I tap one of those empty function
buttons on the tablet, # 12 or 13. Anyone know how?

TIA all,

Alex