Sometimes you just can't do anything, sometimes my Mom-Gyver stuff works. Being an Ex-Special Ed teacher but not big (5"1') I've toileted grown-men in chairs myself. I've talked my son through it. The drop-dead gorgeous EMT who slipped in through an unlocked bedroom window easily lifted me into my wheelchair. The five burly beer belly firemen (volunteers) firemen who once came, broke my storm door and in their eyes I could see unless they threw me over their shoulders like in a fire they didn't have a clue what to do so I talked them through it. Stay calm, instruct as you think best, etc. You know what is best for you, everyone is a little different. That you are thinking about this before it happens and what to do is good. Fear and panic are never good.

Use knees, not backs. Yes, it sucks but somebody should know how to do it.