[Eug-lug] keyboard equivalent?

[dooger watts]

Have searched and searched on this topic, but I haven't yet discovered 
if there's a keyboard equivalent to a hold-down-the-left-mouse-button.

Been doing a lot of drawing/tracing, and, on The Miggy, you could leave 
your left index finger off the mouse button and concentrate on just the 
movement of the drawing cursor by holding down the Alt and Left Amiga 
keys at the same time.

Is there such an equivalent on the PC side?

Thanx, y'all,
M