A search of CTAN has lead me to the 'bytefield' package. This looks like the one I remember hearing about, but I can't find any references in the lyx mail archives.
If anyone has used the tex bytefield package with lyx and has any lyx-specific suggestions, I'd welcome them. Otherwise, I'm just going to install the package and see how it turns out ... -- Devin Reade <[EMAIL PROTECTED]>