I think that the act of being on SO for so long and having so much rep does make you qualified for Meta. It's a higher learning curve, to be sure, but to be honest, getting rep here is so much easier than getting it on SO. There are a lot of opinion-based questions where your opinion would be more than welcome, as such a long-standing member of the SO community.
Do you want something that you think would be beneficial to the site? Don't hesitate to suggest it, unless it's been suggested before. Do you see a question where the answers are opinion-based? Give your opinion!
Actually, one of the fastest ways to get rep here is wait for a terrible, terrible question question or feature request to come along, and then tell them why it's wrong. Sadistic, elitist, and cruel, yes, but true, also yes. Of course, this is assuming that those points don't get deleted, as they often do.
There's room for a lot of people here with a lot of rep. You've been here longer than I have, so you probably know more about the site than I do. Really, the only way to get rep on Meta is to start using it more. My rep hung around really low for the first few months that I was using it; I made terrible feature requests and other posts, but at some point it just clicked, and I started hitting the rep cap a lot more, and getting a lot of rep.
No, seriously. Look at my rep graph. At some point, it just clicked for me, and I got the it that you're talking about, I think.
Stop listening here:
But really, the best way to get rep on MSO is the same way as to get rep on SO. Spend all your time on it. Forget about our smaller sister site we call Stack Overflow. Meta is love, Meta is life.