Adding watchers via custom scrip

I’m trying to add watchers to a newly created ticket via a custom scrip. The goal is to add watchers based on the content of the subject line. Admittedly I don’t really know what I’m doing, but here’s what I added to the “Custom action preparation code” text box (after selecting “Custom Action”):
$Self->_AddWatcher(“Cc”, "Roger@evare.com", 1)

This doesn’t work and the log file has the following:
RT: Scrip 14 Prepare failed: Global symbol “$Self” requires explicit package name at (eval 1961) line 1. Global symbol “@evare” requires explicit package name at (eval 1961) line 1. (/opt/rt3/lib/RT/Action/UserDefined.pm:43)

I’m using RT 3.0.1

Any suggestions?