To be perfectly honest...if a customer called my landscaping company for this tree, I'd likely recommend cutting it down or pulling it out. Roping it straight *could* work but that bend is about as extreme as you are gonna get with that type of tree without it breaking or even uprooting (Did it uproot at all?).
If you do attempt to rope it, for the 'padding' Daisy mentioned, I often use a section of old garden hose that I'll cut down it's length. This way nothing cuts through the bark of the tree while it's under tension. If done right, I promise that rope will hold it...you would be amazed. I usually drive in a fresh, notched metal stake to tie the tree off to. That too, can be an issue if the ground is frozen however (most of this type of work gets done in spring, unless an emergency). Sometimes it take using more than one tie off and in more than one direction as well.
My thinking on the particular tree is this...it's lean is so extreme that you may get it to straighten some...but it's most likely going to develop some odd shaping and branch growth.
Whichever way you decide to go, I wish you the best of luck.
