I'm wondering about a 12v power supply for a power port I'd like to install near the glove box in my 560SEL. The lighter plug is controlled by the ign switch. Not having a good wiring diagram, was wondering if running a + and - leads right from the battery, fused of course, would be a good solution? I'm not sure about any available access holes through the firewall. I've run plenty on US made cars that had the fuse block under the dash drivers side.