Im sure this could be done if you had it on straight PvP and left your guy sitting next to the gem vendor. IF you were trying to do Mixed mode or something I think it would be a bit mroe complicated. Im sure it could be done though.
Im a newbie to profile creating. I can create basic profiles that move to hotspots.
Figured someone could just add a check for when BG is over, to see honor points. If honot exceed 60k it will then goto vendor and purchase said item.