Qole, this one works great: "xdotool click 3" m:0x80 + b:1 + release putting that in xbindkeysrc after installing xdotool, works great. When holding down fn-key, tapping the screen is right click. works in dosbox aswell.
#Shift+Tap=middle click "xdotool click 2" m:0x1 + b:1 + release