Eb,

When you standby for a flight, you'll have to clear into coach first and then request your upgrade. You could ask the GA to standby on the contigency that you would get the upgrade. However as I told a FTer who asked this question yesterday is that even as an EXP I have had little luck in standing by and retaining my upgrade due to high loads and the GA's (fairly) processing upgrades prior to clearing standbys.