Hmm, What I think is that you plan to converge the monitor or a tv's rays through a convex lens of some sort and then you will let the light through another lens to scope the image on the wall. But the concern here will be the intensity of light. Projectors have light amplifiers in them that enhance the light's level to reach the fairly distant wall. Then there will be the problem of mirroring of the image as it is with lenses.
Tell me about your plan in detail, I am excited.