Z offset for use with Precision Piezo Orion?

The extruder.hotend.z_offset config parameter apparently has no effect unless you have multiple extruders. I wanted to set a Z offset in the firmware after getting my Orion hooked up, but had to set it in the slicer instead. Am I missing something in the smoothie config I could use to do this (so I don’t have to copy the setting to different slicers)?