How can I change the speed of the mouse wheeling?

My team found that when the graph is large, the speed of zooming in or out by mouse wheel didn’t meet our need.
How can I change the speed of mouse wheel when I want to zoom in or out.

By the way,I set the wheelBehavior=“Zooms”.

Increase the value of http://goxam.com/2.2/helpWPF/webframe.html#Northwoods.GoWPF~Northwoods.GoXam.CommandHandler~ZoomFactor.html

walter,thx!It is very useful for me and it worked.