Have one big friend (lumberjack, etc) hold the column.

Have another lesser-big friend (lumberjoe) operate the breaker bar with a 10mm Allen bit.

You hold the wheel, and let lumberjoe do the wrenching. If the Allen strips out and breaks loose, the lumberjack gets popped in the jaw by lumberjoe and then you have entertainment on your hands.

Seriously though, big friends. Much grunting.