Years ago I needed to squeeze in a five day trip New York to Osaka on United. I was on a discount coach ticket; I had the miles to upgrade to business outbound on a full fare coach ticket, and I would earn enough miles from that leg to be able to then cover the return upgrade. So I presented this as a straightforward business proposition: I'd upgrade my ticket to full coach if United would loan me the miles to clear both upgrades in advance.
Not only did I accomplish this over the phone (in a wonderful conversation), I then spent twenty minutes at check-in attempting to pay the fare difference to full coach, before giving up and heading to security and my gate. I did sit in business both ways. Or, to be more precise, the return Osaka to SFO leg was rather empty, and I was able to convert a bulkhead middle three seats in business into an incredible lay-flat bed. Even more comfortable than commandeering three rows of five to make a blanket tent on an empty L1011 coach flight.
Alas, I'd bet this was the old United.