I have not upgraded my 1104 to 1108 yet, but if the code has been integrated as-is you should access the spell ID by the $spell_id variable when you are in the event handler function. Here is how I do it on my own version, where I wrote the CAST_ON thingie originally :
Code:
sub EVENT_CAST_ON
{
if($spell_id == 202) # Courage
{
quest::say("Bzzzzt !");
quest::setglobal("A_Bit_of_Clericing", "Guard Buffed", 5, "F");
}
}