What they might be talking about is, rather than using a generic raid frame (standard Blizzard, Xperl, etc) to watch your raid while tanking, instead using an addon targeted at healers (e.g. Healbot). Then instead of binding your actions to heals, you bind them to tank-oriented abilities - say, Righteous Defense or Intercept.
I wouldn't be surprised if someone has done this with VuhDo and made it available, but I cba to search for it because I don't actually tank in the gear I save from being sharded. And if I did, I'd use Grid.