If you can get the first set of runs down at tempo, with the left hand, you can pretty much get the entire piece. I recommend knowing the left hand very well, as it keeps the melody and rhythm. It is very important.
There are a lot of stretchy intervals where you may want to stretch your hand and keep a tense position in your palm. DO NOT DO THIS. When you practice slowly, make sure to keep your elbows loose, but think of them as heavy weights. that when you lift your hand and aim, when you let go, it falls to the key very fast. I know this doesn't make sense, but just remember to keep a closed hand position, do not stretch you fingers out. That is the point of this etude. To learn to play large intervals without stretching and tensing your pentascale hand position. K?
Do not sight read the piece. divide the piece into sections, divide the sections into smaller sections. memorize the right hand. while you play the right hand, sing the left hand to it, or rhythm play it. Then, play the left hand separately. Think about what tempo the left hand should be, and how fast would you have to play the right hand, to make the left hand sound the slow melody fast enough.
Anyways, if you have any questions, I played this etude like a year ago at a few auditions. The best it ever got was then. I highly recommend the BACH WTC. I also played a P&f at the auditions, as well.
I'd work on a couple p&fs at a time, if you like Bach.