Catching avrdude STK500 upload message to reset arduino for wireless uploading


I was wondering whether it is possible to catch the 'upload initiation message' sent by avrdude when uploading through the arduino IDE.
I hoped to catch this message on the serial port (does this message even go to the serial port?), so I can tell the arduino to reset itself to allow the upload.

When connected to USB this happens automatically, but not when only connected by xBee.

In principle i'm using this example to reset the arduino for wireless upload:
This however requires you to send a reset message manually, and then hit upload in a timely fashion; i'm basically trying to let the reset happen automatically.

Any ideas? I found the document containing information on the STK500 protocol and tried to catch the 0x31 message that I assume to be sent in the beginning of the upload, but that doesn't work. Smart | Connected | Secure | Microchip Technology

Hope you can help me! Thanks already!