Try using a slightly smaller metal bar from the other end (e.g. a large cross headed screw driver) to line things up. Wiggle it around a bit at the far end while tapping the pin at the other end, and with Copperslip or other lubricant, it should all line up and the pin should pass through without major banging.
If this is the bar that goes into the footwell, then I used a very long socket extension bar with a 3/4 socket on the end (may have been 7/8), and tapped the end of the bar from the door opening.
Always put the nut on the end of the thread several turns before banging gently, or you will bugger up the thread. Been there, done that.