contrary to what roadstain says, you can bring it up with no clutch, or with a clutch, it all depends on what your comfortable with.
Here is why i do not clutch it up, on more than 1 occasion, i have spun the rear tire while clutching it up, powering it up is more predictable, and smoother.
The downside, you gain more speed when powering it up, but once your good enough, you can sketch off speed, and bring it to what ever speed you want it at.
I ride my long standups, in third, at about 60mph, i bring them up in 2nd, at about 40-60mph, and i have never, i repeat never in about 4yrs of riding wheelies, crashed from doing a wheelie.
Oh and i use the clutch when i shift in a wheelie.