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Thanks for asking.
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