Unfortunately that won't help English speakers, because we would just persist in pronouncing those r's like our "r" in "red".
What helped me to roll r's in other languages was saying something like this really fast like a tongue twister:
"Brother's better bitter butter."
This only works for North American English, of course. Other dialects that actually pronounce the "t's" as t's or turn them into glottal stops won't work. But since the "t" in North American English between vowels is a lot like the Spanish single "r" if you say those words fast enough, it eventually starts becoming "rr". Somehow the tapped t plus the "r" after it seems to do the trick, wheras just saying an "r" alone doesn't help since it's a different kind of r.
