I think temporary stairs would be a waste of time and money. Put in your rough stairs, leave finish treads and riser facings off.
But for lugging stuff down or up a non-skid ramp would be easier on the back and knees, if you have room.
Dollies and carts with a handbrake. A block and tackle for letting really heavy loads down the ramp.
Make the landing floor area as big as you can without making stairs too steep. It'll make it easier to turn the corner if you're ever carrying any large piece of furniture or something around it. If the back door is not a straight shot into basement stairs bigger landing will help get your materials down there.
[CENTER][FONT=Comic Sans MS]Measure twice, cut once.[/FONT][/CENTER]
[CENTER][FONT=Comic Sans MS]Look at the nail, not the hammer. Watch the fence, not the blade.[/FONT][/CENTER]
[CENTER][FONT=Comic Sans MS]If you hook your thumb over your belt you won't hit it with the hammer or leave it layin on the saw table.[/FONT][/CENTER]