It depends what you want to do with it, do you only want to log it or show it on screen?
If logging and using the megaloggerHD only this should be enough:
open datalogger.h
define your PID, for example "#define PID_NOX 0x83"
add it in the const PID_NAME (for example "{PID_NOX, {'N','O','X'}},")
How to add Bit encoded PIDs such as 0x83 NOx sensor?