Draw Polyline without mouse button? (odd question I know...)

Hello all,

I was wondering if there is a way that I can draw out a polyline by pressing a keyboard key instead of the mouse button no. 1.

I am tracing in some old contour maps and I would like to be able to enter each point without using the mouse button.  That way I can focus my one hand on the mouse position and the other hand can enter the points.  It will be faster for me.

Thank you