'91 Regal Firewall Grommet

I am installing a subwoofer system in my 91 buick regal. I have 90% of the wiring done, the only thing that is stopping me is that i cant find a hole or grommet in the firewall anywhere to run the power line from the amp to my battery. If any of you guys could explain where i would find one or have pictures it would be greatly appreciated. I can drill a hole if i have to, but i would definately prefer not to.

Thanks

i just decided to pay the $30 to have Circuit City go through the trouble of drilling through my firewall to install the power cable. i didnt see any way i could do it without hurting something.. but now everything works and its freakin awesome