Please note first that changing to the left click isn't practical and may conflict with another key binding, like the menus.
But you can use
ccsm to initiate another key for showing the mouse location:
If you don't have
ccsm: Install From Here
You also need the package
compiz-plugins-extra. You can find it in the Ubuntu Software Center.
Go to CompizConfig Settings Manager > Accessibly > Show Mouse:
Use This Plugin left menu: check
Enable Show mouse.
- Change the mouse
Initiate key binding as below.
To determine the meaning of Compiz button numbers, check this answer.
- Button 1 is generally the Left click
- Button 2 is generally the Middle or Right click
To take effect, you might need to "restart" Compiz:
compiz --replace &