Is there a way to add the GRASS v.centerline function to the QGIS Toolbox GRASS functions?

Question

The standard GRASS plugin in QGIS does not include the v.centerline function in the Toolbox.. it may be an extension that needs to be added.. is there a way to add v.centerline to the GRASS functions in the QGIS toolbox? Would prefer not having to try and learn using the separate GRASS environment to try and use v.centerline.

Tried finding procedure on web to add v.centerline as extension to GRASS functions in QGIS Toolbox, but without success..