Jan: Disclaimer: I don't know this joseki at all, and have not looked at the corresponding SL pages (or if I have, I don't remember them :)
OK, I assume Black played his first move on the 5-4 point with the idea to get a position along the upper side. Just trying out some ideas below, to see what they look like...
If the upper side is important, Black can play one. White will probably take a (or b??)
unkx80: I think Black 1 is way too weak. White 2 will play at a.
unkx80: Of course this variation is favourable for Black. =) So it is unacceptable for White to allow Black to have a ponnuki with 3.
Here Black is happy to get or attack the corner instead. I haven't looked at other options for white 2 yet.
unkx80: How about White 4 at a?
Alex Weldon: I like the first move of the second idea (atari at 1), but if White cuts at a, it gets complicated. What about Black using 3 to connect?
To my 10k eyes, this looks much better for Black in the ensuing fight, especially if the ladder works. Alternately, Black can let the outside White stones live and take the corner.
Bill: Well, yes, but isn't this too easy on White? Look at the previous diagram, where Black 5 extends. White is left with three, count'em, three weak groups. White can hardly stand it.
As a variation on this, Black can take gote for more influence down the left side.
unkx80: Yes, I am expecting Alex Weldon's answer, short and sweet, easy to understand and easy to play. =)