So basically what this does, is devoice anyone that joins your ustream chat that isn't a auto-op, or you. The reason this is necessary and you should use it, is because ustreams bot auto voices people, and if you want to +m the chat, they can still talk, if you have this script however, they will not be able to talk during +m's.
on @*:JOIN:#: {
if ($network == Ustream) {
mode $chan -v $nick
}
}
;Alternately, the more clean version
on !@*:join:#: { if ($network == Ustream) { mode # -v $nick } }