Scale about true center with Mirror modifier When I scale vertices of an object that has a Mirror modifier, the points scale about the median of the non-mirrored points only. How can I configure Blender to include the mirrored points in the calculation of the origin?
Snap Cursor to Selected.
In the Properties shelf, for the mirrored axis, subtract the Median location from the 3D cursor location. 
Set 3D Cursor as Pivot.
Scale.