SoftSwitch is a memory resident program that allows you to control an IBM compatible PC using one or more switches. This could be one or more switch plates, a switch based joystick or even a proportional joystick - really anything that can provide a switch closure (or open).
SoftSwitch comes with lots of switch aware programs including a menu system, lots of useful utilities like sticky key and no repeat, and supports various scanning modes, an onscreen keyboard and morse code. It is primarily intended for DOS based programs, but can be used in Windows 3.1 and 95/98 to simulate a mouse. Will also operate in Dosbox on a Win32 or Win64 platform using mouse buttons as switches - use ss /o at the command line.