There is a possibility they will come with some kind of wall brackets anyway, which you may have to modify (bend) to get them to point downwards,
i hate wires too, its a pet hate of mine, what i did for the rear surround sound speakers at least was to chizel a small groove into the plaster right in each corner (used a screw driver) and then skimmed over with plaster then papered over the top, a bit extreme i know but well worth the effort

they look a decent piece of kit.
if you had to fabricate something from scratch, then it wouldnt be that difficult to make some small brackets, as long as you have a drill, hacksaw and bit of flat metal, you could always then spray it to match