I still have just the strap of my heart-rate monitor, but I decided to try it out at the gym to see if I could get the hang of this type of training. The treadmills are compatible with the strap, and they have programs that automatically adjust the incline so you can hold your heart rate wherever you want it.
I thought it would probably be pretty easy to do the whole walk/run at 65%, but that actually turned out to be a bit harder than I've been walking (uh-oh). In fact, I thought I was doomed at first, because it took some very steep, very fast treading to get my heart rate up to the magic 118 and I kind of got out of breath. (Starting to wonder if I am the world's wimpiest walker.) When I jogged, though, I literally could not go slow enough to get it down to 118, but at least it was flat, and I felt more relaxed.
My resting heart rate is pretty low (although I'd like to find my watch and actually measure it), so I wonder if I might need to adjust the training ranges down from what the treadmill suggests. More research!