<p>I have a sharepoint event handler which I want to activate for a single list, not all the lists in the site. How do I go about this?</p>

Just that list or that list in each site ?
I have been testing the code that run when the event happens and I have used a
nice little tool
from u2u, which allows me to add or remove event handlers per list.
This MSDN article
is a nice primer.