A script can only modify the behaviour of the copy of mIRC that it is loaded into.
Redirect all private notices to the #help window:
on 1:NOTICE:*:?: {
var %nick = $(-,$nick,-)
echo $color(notice) #help %nick $1-
}
Redirect all private notices to the active window:
on 1:NOTICE:*:?: {
var %nick = $(-,$nick,-)
echo $color(notice) $active %nick $1-
}