There are 2 commands
plrfreeze=X which disables keys for x milliseconds, but lets the player look around and shoot their gun.
plrdisable=x which disables keys and mouse for x milliseconds
Edit
The way I use it in a triggerzone would be to set it up where once the player enters the zone they freeze for the length of the sound. if the sound lasts for 5 seconds then the script would look like this.
:state=0,plrwithinzone=1:sound=[sound you want],state=1
:state=1:plrdisable=5000,state=2
If you are using V19 then there is an additional command you can use.
soundfinished=X X=1 not playing sound X=0 Playing sound
this would allow you to do this with the script.
:state=0,plrwithinzone=1:plrdisable=999999,sound=[sound you want],state=1
:state=1,soundfinished=1:plrdisable=0,state=2
Note that I was using plrdisable for these. it can easily be change to plrfreeze if you want the player to be able to look around.