Originally Posted by
aacharya
You don't. There is no mechanism for free upgrades** to CO BusinessFirst flights.
**Apart from the occasional op-up (when Y is overbooked).
To be clear - Chance of OPUP is slim to nil for 2P. If any overbooking, OP comes after GS & 1K on elite heavy TPAC. You should call CO ASAP and get the details of what might be available for SWU, miles, etc. Even those are a long shot.