In general yes, idle up and mid stick is where you want to center the servo arms. The idea is that you want to center the servo arms when the blades are at 0 pitch, and the most common idle up curve has zero pitch at mid stick. But if you have a different setup this won't work, so don't just blindly put your TX in that setting
Also, you obviously will have to unplug the motor.
What I did in the DX7 is set the pitch curve for throttle hold so that it covers the whole range from max neg pitch to max pos pitch with 0 pitch at midstick. Basically the same as your normal 3D idle up pitch curve but this way I can just flip on throttle hold to do all my pitch adjustments without disconnecting the motor.