wireless input using Firmata: Rx pin not necessary

I am using an arduino nano to provide sensor input to max/msp via xbee radios. Understandably, having the xbee connected to the Rx pin is not necessary for transmitting sensor data to max. Leaving the pin free has two advantages:

1) New .pdes can be uploaded via usb without disconnecting or powering down the xbee.

2) The Rx pin can be used for something else while the .pde is running.

However, in the current Firmata digital inputs seem to be disabled by default. The corresponding max firmata patches can send a signal to the arduino to enable digital input, but this requires the xbee to be connected to the Rx pin.

Can anyone tell me how to alter firmata.cpp, firmata.h or a generic firmata .pde so that digital input is enabled by default? Note that here I am not refering to the pin mode of the individual digital pins.