Started looking into activation devices. Ouch, it does not pay to be disabled. This switch cost $101 USD at the time of this writing (and that they indicate is with a 30% discount:

http://www.rehabmart.com/product/tongue-switch-45212.html?gclid=CjwKEAjw5M3GBRCTvpK4osqj4X4SJAABRJNCY0kzFNBknVXYkw0T5H63sBnamY-TSUikykqfOIZ1ihoCRwfw_wcB

The nice thing about this switch is that it has a 3.5mm plug:

Switch size: 1½"L x ¼"D. Cord length: 6 feet. Plug: 3.5 mm. Weight: 2 oz.