Hi,
Your best bet is to use some wireless joystick or mouse. Check out the following site,
http://ilab.cs.ucsb.edu/projects/ismo/fogscreen.html
They created a wireless joystick with a ppt light embedded in it (scroll half way down the page).
You can also purchase special remote controls for computers that can map a button to a specific key press. This might be overkill in your case.
Contact
support@worldviz.com for information about acquiring extra LEDs for the PPT.