I too had Marlite walls in my bathroom, however it only went up as far as a standard chair rail. First I sanded the shine off of it, then applied a good primer. Then painted it to match the upper portion of the wall. There was already a smooth, plain chair rail, so I painted that too. When all was finished, I stenciled a small ivy print on the rail. I was afraid that the paint would start to peel, but after several years, it's as good as new! Hope this helps!