[Throbber]

I fitted a power distribution module to run sat-nav & heated clothing etc which needed a switched live. To get the switched live I tapped into the rear brake light switch. That's pretty straight-forward to do. I bought a male & female connector of the same type that is used for the brake light switch and made a short section which included a third cable for the switched live. That way I didn't have to cut into any wires and I can remove it if/when required.

There's probably not much choice for a permanent live feed as your options, other than the battery are probably limited to the short section of wiring between the battery/fuse-box and ignition switch.