If you mean taking a fall directly backwards, and folding in your shoulder blades to protect your spine? (I'm guessing here that this might be what you mean), don't think I'd like to do that.
I think we're talking about the same thing. Essentially - taking ukemi from shihonage by "doing the limbo." The first part of your body to make contact is your outstretched arm followed by your upper back/shoulder blade. Your butt never hits.
Can any Yoshi guys out there explain why the shihonage ukemi is sometimes practiced this way?