I don't have a specific answer, but typically there are unused gromets
in a firewall for running wires. You could just hunt around for one.
If running it on the drivers side make sure you are clear of any pedal
and steering mechanisims.

Here is what is important: You need to have a fuse on the wire at the
battery end. Typically the device (converter) has a fuse on it but
that still leaves the entire run of the wire unfused. If it shorts it
will start a fire. So, use a fuse at the battery end too. (As a young
man I worked in a auto stereo shop and I saw more then one wiring
loom burned when the wire shorted as it passed through a firewall or
was pinched under a seat bracket -- a fuse at the battery would have
prevented that.)