you even decide you do not like the tile, you can simply crack a few and then pull the entire board off leaving the clean wood on the original stairs behind. or simply tile the small boards that fit in the space and using wood trim trim the tiled panel out to hold it into place. this way you can tile everything on a table and when dry simply put them in place and fasten them in. like any tile job, clean and no bumps on the wood. using a good quality thin set should do the trick. be sure to back butter the tiles so they stick as good 