This is the bind, put it in your autoexec.. If you don't know how you need a different guide.. Change mouse5 to whatever you like... Ajust as needed..

//One Click Frag: To use, press your BIND and hold until pin is pulled.
//Keep held to cook as desired, then release to throw.
//You will then cycle back you last inventory.
//(This uses standard throw, not underhand)

alias "+ocfrag" "slot4; +sprint; +attack;"
alias "-ocfrag" "-attack; -sprint; lastinv;"
bind "mouse5" "+ocfrag"