Bind SPACE "+crouchjump"
bind CTRL "+duckfix"

alias nocmd ""

// Crouch jump, shallow water compliant + duck fix
alias +crouchjump "+jump; wait 5; df_duck"
alias -crouchjump "wait 5; -jump; df_stand"
alias df_duck "+duck"
alias df_stand "-duck"
alias +duckfix "+duck; alias df_duck nocmd; alias df_stand nocmd"
alias -duckfix "-duck; alias df_duck +duck; alias df_stand -duck"

Crouch jump is incredibly handy but the scripts here have some annoying bugs.

First you can't jump in shallow water, this was fixed by simply delaying the crouching (AegisXOR) and pressing jump, holding duck, releasing jump made your character stand back up again (even if you didn't release duck).

This caused me to die a lot :( So I fixed it.

Put script in autoexec.cfg and bind +crouchjump to SPACE and +duckfix to CTRL (or whatever keys you like)

Enjoy.