yqt I am using the same old flash as you, I don't even have an omnibounce.
I just set the flash first and shot, shot, shot. Bounce off anything that I can find, last night take picture of my daughter, hand held with slow shurtter speed ( I think that it was like 1sec) for movement with rear curtain sync bounced from the top, came out all right. I always set the flash for wide coverage. Stray light can bounce off wall to soften shadows.