He gave you an example with it already done...
Just change this line:
if ($3 != n00b) && ($3 != loser) && ($3 != fail) && ($3 != leech) { notice $nick ( $+ $3 $+ ) Is an incorrect label! }
to:
if (!$istok(n00b|loser|fail|leech,$3,124)) { notice $nick ( $+ $3 $+ ) Is an incorrect label! }
Actually, he even went further than that and rewrote the entire thing for you.. lol