What bugs me is the part "If the airplane is properly rigged, this should result in an approximately neutral wheel", because most of the time when I trim the airplane (737NG) according to this procedure I get an approximately 0,5 to sometimes even 1 unit right wing down indication on the control wheel.
Prior to this statement only the "rudder" has been trimmed. The "rudder' is not connected to the control wheel. So control wheel should be in neutral position.
With the autopilot disengaged, hold the wings level with the control wheel using the ADI for reference. Trim out any control wheel forces using aileron trim.
Note: Use of aileron trim with the autopilot engagaed is prohibited.
If desired, re-engage the autopilot.
This step trims the "ailerons". Any movement of the "roll trim wheel" will result in wheel displacement, as the wheel is connected directly to the ailerons.