Z-BRUSH: SpotLight

General Z-Brush Shortcuts

SHIFT+Z = show / hide Spotlight
z = enable / disable paint mode

" , " (comma) = show / hide Lightbox

In order for Spotlight painting to work, you have to double click on the texture in Lightbox to load the texture into the texture editor.  From there, you have to 'Add To Spotlight' in the texture panel.