Flooring Tile - Tiling a painted wood bathroom wall

I recently moved into an old house - circa somewhere between 1880 - 1901 (depending on who you talk to).

The upstairs bathroom has what equates to hardwood flooring for walls. Horizontal waynescoting (sp?) if you will.

This stuff has numerous coats of paint on it - I'm currently in the process of stripping the paint and plan to ceramic tile half way up the wall - (painting the rest of the exposed wood up to the ceiling)so here's my question...

Should I even be considering tiling over this wood? I.e. - will there be mastic adhesion problems if I don't get all of the paint off, etc?

Thanks

the tile would only be stuck as good as the paint is. alternative could be install 1/2" concrete backer board then tile to that you would use trim pcs. on top that is called mud cap that cuvres enough to cover the 1/2" backer board.