Another option would be to use a push button with an led inside that lights up when you press it and turns off when pressed again therefore giving you an indication that it is turned on and only giving you one press of the button on the keyboard instead of constant pressure.
Kevin,
The cheap switches with the internal lighting usually use the power that they are actually switching (x V DC) to power the led. Since you really don't have much voltage on the line you are switching... it won;t likely drive the led. You can get ones that have the led power separate from the poles of the switch..... but they are more expensive.
Be VERY careful when mixing DC (or AC) supply voltages on switches that are connected to interface modules. You can fry the interface board easily if you get the wrong thng in the wrong place .
best,
..................john
PS: Like your "cam" idea.