You are on the right track with the hoofbeats, Ms. Skywalker, but it's not that simple. Keep with it.
Samwise, is the line you're thinking of possible "Noro lim, noro lim, Asfaloth!"? (Ride on, ride on, Asfaloth!)
The answer was listed as an "Easter Egg" in a newstand magazine shortly before RotK came out. Unfortunately, I don't remember which magazine
so I can't help you there. I don't know if its available in other countries, either.