I don't have any experience with the OTA Zeon, and usually my stuff has outdrive "rings" rather than clips. Try to work on one side with your finger and then use your thumb to push up on the opposite cup to force the other end on while applying pressure with your finger on the clip (if that makes any sense
). I've never had trouble installing them, but rather taking them off is the pain.
i'm assuming that plastic sleeve slides over the outdrive and the clip locks it in? i'd imagine it would be the same concept. might help to gently squeeze the outdrive with some needle nose pliers. just be careful not to squeeze too hard or mar the outdrive.