Well.... I'll tell you what a drummer told me once when I expressed how difficult it was for me to just play simple beats, just to have the sticks feel right.
"What did you expect?"
If that lick takes you a year, it takes a year. If it takes 20 years, it takes 20 years. It's not supposed to be easy. It's supposed to help you play somewhat like Eric Clapton, which is a lot different than the guy you just heard playing down at the local Guitar Center.
I would experiment with barring the eb strings and see what that gets you. Also the 6 5 - 3 ... that 5 can be a pulloff too and if you stumble on that it throws everything off.
The 5 5 5 thing on b and g strings is almost like a barre but it's just rocking back an forth to play/mute the string... and again that's a move that needs to be clean.
Also play it with Index and Ring... I'm pretty sure EC is a 2 finger Blues lick guy. That too puts your hand in a different shape and when you get to that 6 5 - 3 the middle finger drops right on the 5.
So over all there is some two string hand rocking going on. Not one string at a time. eb then gb.
That's all I got.