Well, if you're sure you want this, then here is a method that will work and hopefully help prevent problems with flooding...
on *:text:*:#yourchan: {
if (%away. [ $+ [ $nick ] ] == $null) {
msg $nick $awaymsg
set -u60 $+(%,away.,$nick) 1
}
}
That will make it only respond to a specific nick once ever minute, but allow it to still respond to any other nick. Replace #yourchan.