Yes, you can use the Baader Solar Film with telescopes too. Make the cardboard strips deeper for a telescope, say 70/80mm. The Baader sheets are 8 inches wide so you should be able to make a full aperture filter for a 6 inch scope with a 1 inch overlap. You'll need a filter for the finderscope too.
Use whichever instrument you feel most comfortable with, binoculars or scope. If the scope, do practice setting it up beforehand. Remember what Dave said about viewing when picking your viewing spot.
  