I was at the Back Wall last week.
The walk in to the top of the back wall is pretty cruisy. Probably takes 70min without rushing. The rap down is nicely bolted and pretty easy to find.
Unfortunately we only took the photo from the 2006 guide, which is pretty terrible for some routes (we were after Quartz Route). It was a big mistake not to take the photos and topos available from the VCC website, they would have helped alot.
My partner was unwilling to launch up into uncertain terrain (I think we were a little to the left of the QR, trying to identify features); so we suffered through several extremely unpleasant hours scrambling up a steep, loose, densely overgrown gully. Classic Buffalo. At the time I swore to myself if it happens again, I would solo to the top.
It can be hard to get a sense of perspective from the bottom of the Back Wall as it is jumbled and overgrown in places, so it may aid things some to go to the lookout at the Horn car park first, eye your line, and get a sense of where and how far you need to go once you get to the bottom. Unfortunately from this perspective you do not get a great sense of the gullies that divide the cliff.
Have a great time.