Can pointing device be manually loaded?

Hello all again:
This is another question relating to my Sony Vaio running Red Hat 7.1, but
it's not really specific to that system. When I'm traveling, I use the track
pad or a USB trackball. At home, when I hook it up to my KVM switch (so I
can use my preferred setup) I use the serial port for the pointing device
(for rather complicated reasons I don't want to go into here.) The problem
is, when I change setups, Kudzu sometimes has trouble recognizing the change.
And I hate to have to reboot the system just because I've stuck the USB
trackball on. So, the question is: is there a way to manually force Gnome to
change the pointing device, perhaps with some sort of command-line script? I
suppose I could have three versions of XF86Config-4, and restart X each time,
but I was hoping for something a little easier...

Thanks,
Vaughn