There are 6 user bytes that get sent back to the OI, along with the PWM information for PWM outputs 1-16. A few other things get sent back as well; take a look at the packet spec to get all the details.
To set a user byte, you do something like
Look in ifi_aliases.h for the exact names of all the user bytes.
This LabVIEW code is a great place to start:
http://www.chiefdelphi.com/forums/sh...71&postcount=8