Sculpting along curve, how do you do it?

Ok, can’t figure this out. How do you sculpt along curve? I changed to curve, hit the plus to add a new curve, then hit the draw button. Nothing seems to happen and I can’t really find anything online on how you do it.

like post # 5 in this thread https://blenderartists.org/forum/showthread.php?403349-Brush-along-path&highlight=Sculpt+along+curve

finally found my answer here https://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.72/Painting
didn’t know you had to use ctrl to draw.