Calcamine??

Does anyone know how to cover dark green calcamine?? I am peeling about 8 layers of wallpaper at my dad's house in the living room. Half of the room has the wallpaper glued right to the plaster and half of it has calcamine painted on the plaster under the wallpaper. The paper on the unpainted side is hard to get off, but the calcamine side peels like nobodies business. I had calcamine in my upstairs hallway and put some kind of sealer on it that my MIL bought, but I can't remember what kind it was. Would you suggest an oil based sealer?? I would like to texture the walls as they aren't the straightest, and I don't want the joint compound to fall off if it doesn't stick. I am a remodeling newbie and the way things are going, this is my first and last project!! ;)
Thanks
Ruth