You have to use a "point_viewcontrol_multiplayer" entity (or their relatives) then trigger it.
Example:
PHP Code:
add:
{
"origin" "10 20 30"
"angles" "0 -180 0"
"targetname" "camera_test"
"spawnflags" "1"
"interp_time" "1.0"
"fov_rate" "1.0"
"fov" "90"
"classname" "point_viewcontrol_multiplayer"
}
;then to activate you have to trigger it like that
add:
{
"targetname" "relay_camera_test"
"classname" "logic_relay"
"OnTrigger" "camera_test,Enable,,1.0,-1"
"OnTrigger" "camera_test,Disable,,7.0,-1"
}
You can test it in console with
PHP Code:
ent_fire camera_test Enable