I thought I would get my two pence-worth in on this topic...
I agree with wharris on this matter..
Now, not claiming to be a professional at playing guitar, I have been playing for 11/12 years or so now.. I am 26 years old and in the last 2/3 years or so my playing has come on leaps and bounds... even more so for listening to artists such as Joe, Eric Johnson, Eric Gales etc..
Having taught guitar for the past 6 or thereabout years to students of all levels/ages... a common problem most have encountered is patience. And believe me, patience really is the virtue in this instance.. Teaching allows me to study the physical emotional output by my students in regards to their own reaction to their playing achievements. When they make a mistake, you can tell they are set back by it, but by pure ignorance, they do not take a step back to think about, why they messed up, what went wrong, and how to find a way around the problem.
As I mentioned earlier having influences such as people like Joe, (who I actually got into many, many years ago, and sort of passed over him) and like i say in the past 4 years or so I had back tracked and got back into him, and his playing ability in the sense that it is such a pure & clean style, (whatever genre he is attempting). He even states this in his playing that he has over the years, decreased the amount of gain that he uses to give the said, clean and articulate style which we know today..
anywho,, going off track a bit ill get back to it..
Playing SLOW really is the key to learning those tricky lines. Muscle Memory is and should be one of the most fundamental parts of any guitar players technique, specifically while learning/practicing/performing..
And having followed this particular thread for a while, in most of Joe's fast pentatonic runs, I personally believe he does pick most of his, and yes people it is impossible without the practice but like i say if you do slow it down and practice it in three parts, Learn It Practice It & then Perform It you will soon enough be playing the same licks...
I may just post a couple of video's so demonstrate all of this in action, and some of his particular runs if anyone is interested..
I apologise if this seems like a load of babble, what with being my first post, but Having followed this forum for a while & noticing that I had never posted (i spent too much time reading & enjoying other peoples posts) i thought i would start to commit to posting 
