There's a more efficient solution to what you want to achieve:

You can create custom actions for the left and right button that - depending on whether you view live or recorded tv - send different AppleScript commands to EyeTV.

Other than that, the default mapping is already pretty close to what you want: if you use it, you already do get rewind/fast forward on long presses and channel switching on short presses, though.

Best regards, 
Felix Schwarz