So there's an online Japanese mahjong league for English-speaking players going on right now: something I was hoping would one day exist for me to participate in. And so I am, and if you play, you should give it a shot too. The league page is here, and the nuts and bolts of the process are here.
To put it more simply, register an ID on Tenhou and play in the 7447 lobby, which has long been the unranked lobby English-speaking players use. The folks running the league do the rest. 20 games are enough to put you formally into the league.
It is different from a conventional league or tournament in that you can play whenever you want, and the goal is just to play as many games as is possible. Specifically, from the explanation:"The catch is that scores will be calculated from the brute scores, rather than the net scores (Finishing with 23300 (after the placement bonus) will net you 23 points, not -7), putting pressure on players who do not participate enough."
In other words, your ranking is a cumulative score of every game you have played in 7447 over the time period. You can't lose points unless you actually bust out of a game. With that one exception, winning (or even worrying much about one's placement, which the Tenhou ladder system strongly enforces) is not so much the goal of the league, because unless you lose very badly, there's no punishment for losing.
Rather, it is just to grind out as many matches as you have time for, because every game will add points no matter how you do. Obviously you still want to get a lot of points in those games, but it's vastly more important to just keep playing over and over again. The explanation post says as much. The way the ranking has panned out makes the result of this approach clear: skill level is irrelevant. The top guys are approaching 200 games: that's roughly 100 hours in a month. A part-time job. The sheer hours put in are what is important.
(I'm トリプルブレイク, Triple Break, if you're wondering how low-ranked I am in the league to be making these complaints!)
So as a competition, I can't take it too seriously and probably won't participate much further than the mandatory 20 games. I'd rather put that energy into Tenhou's normal ranked ladder, which presents more substantial long-term motivation. As a ploy to get people's asses into 7447 and bring the community together (which I believe is its actual purpose), on the other hand, I think it's a clear success.
As a related note, I now stream Tenhou rounds on twitch.tv. There is no hard schedule, but I tend to stream in the area of 8-12 PM.