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Thanks for asking.
You can customize the actions for the "Select" button, with the "Play/Pause" button performing the same action.
The problem at hand is that Apple used a smart tweak while adding the extra button: it sends the same IR code for both the "Select" and "Play/Pause" button, but sends an additional, special IR code when you press the "Play/Pause" button. These two IR codes are sent in such rapid succession that they're not always reliably received/decoded by EyeTV receivers.
Support could be added for the "Play/Pause" button, but it would not be reliable. If an estimated 50% of the time, the extra button is not recognized correctly, however, and another action gets executed, all that would cause is frustration. That's why there's no support for the additional "Play/Pause" button on the aluminum models.
That said, Remote Buddy does support the extra button with all other external receivers (f.ex. eHome/MCE).
Best regards,
Felix Schwarz