//this firmware and document modified from Arduino's source.
To setup the project and upload the RAMBo usbserial application firmware to an ATMEGA32U2 using the USB DFU bootloader:
1. unpack the source into LUFA's Projects directory
2. set ARDUINO_MODEL_PID in the makefile as appropriate
3. do "make clean; make"
4. put the 8U2 into USB DFU mode:
4.a. assert and hold the 8U2's RESET line
4.b. assert and hold the 8U2's HWB line
4.c. release the 8U2's RESET line
4.d. release the 8U2's HWB line
5. confirm that the board enumerates as either "Arduino Uno DFU" or "Arduino Mega 2560 DFU"
6. do "make dfu" (OS X or Linux - dfu-programmer must be installed first) or "make flip" (Windows - Flip must be installed first) or use the AVR Flip app.

Check that the board enumerates as either "RAMBo". You may also need to upload stk500v2 bootloader to the 2560 if it is not already. 
Test by uploading a new Arduino sketch from the Arduino IDE.