Your flying the same day and you want a upgrade processed by EUA?

I take it that your company must have negotiated discounts, hence the inability to e-ticket (instead you are on a prepaid ticket).

I believe that EUA normally runs full Y tickets 2 DAYS before departure. If you buy after that you may get run at midnight, but when you buy the day of the flight you may be in the middle on ANY airline not just CO.

I'd suggest trying to ask for a better coach seat at the gate as well as getting on the standby list. From what I understand you will get on before the companions if it comes down to the standby list at the airport.