Hi Todd,
You'll get diametrically opposed opinions on this, but I'm in the 'don't risk your airplane doing fast taxi runs' camp. In my opinion (with around a thousand t/w hours and about 30 nose wheel hours), running a taildragger down a runway at high speed while trying to *prevent* a takeoff is begging for disaster. It really doesn't teach you anything because you never do this in normal operation. And you've added a *lot* of workload, because you must both keep the tail in exactly the right attitude to prevent liftoff without dinging the prop, and play meatpuppet cruise control with the throttle, for the same reasons. All that while performing the normal duty of keeping the plane straight on the runway. I equate it to trying to balance on one foot on a basketball, instead of dribbling it. For you, maybe spinning a hockey puck on one finger while skating & maneuvering another puck with your stick. Why try? :-)
If the runway's long enough and I felt compelled to practice while tied to the ground, I'd perform a normal takeoff to well above stall speed, then smoothly pull power & perform a normal landing. But if you're completely new to taildraggers, I wouldn't be doing any of that stuff without an instructor in the right seat, until he tells you you're ok to play alone. Why risk your plane?
FWIW,
Charlie