need to get through firewall

92 Cutlass Supreme 3.1
I am trying to install an amplifier for my cd player. I need to pass the power cord for the amp from the passenger compartment through the firewall into the engine compartment. I can not find a hole from the inside to do this, anyone know where I can find this... please help.

I have a 95 olds cutlass supreme so they should be the same. I put an amp in my car and ran the power wire through the rubber gromet where the wire for the gas pedal goes through the firewall. Its a bit tough to do but the only spot i think that works. Hope this helps.