I've been using cement dye in lime mortar to point up around
prefinished windows (windows dark stain on meranti, lime mortar with
yellow dye to match local sandstone colour). Yes, I've succesfully used
masking tape on the frames to minimise staining. For the small amount
of paving/tiling I've done (fire hearths), I've just used care - and
yes there is a little bit of staining - but it looks right on irregular
reclaimed building materials.