I think the reason why toning lith prints is interesting is that highlights are built differently than with standard chemistry, it's mostly a tone of color, which I believe comes from an oxidation process.
I tried selenium toning a lith print made on Agfa Portriga Rapid the other day, and all of the glorious highlight tones just disappeared, and faded into gray. The black and gray turned, as expected, to a dark copper brown after a while, while the highlights remained very bleak and looking washed out. I suspect brown toner might have a similar effect. I know that when I bleach lith prints and re-develop in sepia, the highlights come back, or most of them anyway, which is why I overexpose those prints in the enlarger by about a half stop. The highlights come back nicer that way. And then it's only after the print has been toned in sepia that the selenium really starts to look good to my eyes.
Trial and error - get your hands wet, Kal, and let us know how it went...
Or, I have some Kodak Brown toner at the house, I might try it myself.
- Thomas