My best advice?
Start with low power wheelies and work your way up over time.
Use a quick turn throttle, it'll help immensely. Faster opening, easier to get it up, and the faster closing rate allows the engine braking to do its thing, negating any desire to touch the rear brake.
As for the rear brake? In 20 years of riding I've not once needed to use the rear brake to level out a wheelie, even with many hours ripping around on CR500's and 70-115 mph high speed wheelies on the hayabusa. Throttle control is key to success.