To build your own cable for use with ECMspy you will need the following parts and information (Thanks to Jmhinkle at BadWeb):

This cable from Mouser Electronics converts the USB signals to TTY that the ECM understands.
Also needed is the Deutcsh Connector plug kit from an ebay seller to connect the cable to the ECM plug on the bike.


The pinout is (numbers as printed on the back side of the plug):
1 - orange (ECM receive, Rx)
2 - black (Ground)
3 - yellow (ECM transmit, Tx)
4 - n/c