It's possible that some of Schoenberg's Sprechstimmung notation is close to what you are looking at. In works such as A Survivor from Warsaw or the Ode to Napoleon, he used a single line without a clef, with ledger lines above and below the "staff", and even with accidentals, although these are bit "impressionistic" without an idea of where Do is, and might be too imprecise for what you're looking at.
He also came up with a chromatic notation system that might serve well without clefs - it's fairly extensible, accommodates standard rhythmic notation well. Musicnotation.org (Dave's link) has a bit about it, but the real detail is to be found in his book Style and Idea.