"What, you don't have a spare mouse? There a good chance you do
have a second pointing device, though — even if it's a mouse
and the built-in trackpad on your laptop. But this process will
work for any pointing hardware recognized by X, including a
trackball and a mouse, or even a mouse and a pen tablet.
To X, they are all the same. You will need to ensure that you
are running the X.org X server 1.7 or later to use the feature in
questions, Multi-Pointer X (MPX). You almost certainly already are
— X.org 1.7 was finalized in 2009, and all mainstream
distributions follow X.org closely. Bring up your distribution's
package manager and install the libxi and libxcursor development
packages as well; they will come in handy later.