bind "X" "sm_checkpoint; sm_cpsave" for saving. bind "X" "sm_gocheck; sm_cptele" for teleporting. These will work on both HoC #1 and #2.
Hmm, maybe they added sm_cpsave as a command to KZtimer as well. I guess you could just bind it once then if you wan't to play on HoC #2. So just bind "X" "sm_checkpoint".
It's activating twice: once on press, and again on release. You can see this in console. It's normal, doesn't affect anything.
Its actually a good thing that I've noticed. It allows you the press the bind right before you land and usually succeeds in placing a checkpoint even if you are in mid air because of the secondary checkpoint.