i cant seem to fine a good place to pass through the firewall. any help would be appreciated.

There are some safe drilling spots in the firewall, up above & behind the brake pedal in fact I think there's a rubber plug there, not sure.

In my i30, I've run wires up under the kickpanels and through to the wheel well, then back into the engine bay. You'll need to take your wheel off to do this, but it works well and I've put several wires through that way.

If your car is an auto, then buy a water-proof grommet and drill the firewall and install it where the clutch usually goes. These work extremely well and allow the addition of extra wires by just loosening the cap and feeding them through the opening. When u finish just tighten the cap and it will seal the opening.