Tried as I did, I couldn't put'em on with my hands. I ended up dropping on on the ground, having to pick out the sand/leaves.
I then grabbed a suction cup, the kind you might find on the back of a bathtub pillow or a window mounted radar detector. They were a piece of cake to install using this method!
Stick the suction cup to the center of the blackout, placing it (blackout) into the desired position, then pressing it (blackout) into place. BaddaBing!
(Do note.. that the blackouts have a cut out for the top screw holding the taillights on, so there's only one way to position them into place...at least on a C6)
GS.Creations is where I got mine from for $99.00 I do believe.