Well you have:
2 power wires that go to the battery
Then 2 grounds.

Run the power wire from the starter directly to the battery in the trunk

The next power wire goes from the fusebox to the battery...

Or

you can run the cable from the starter to either a distribution block in the engine bay or a distribution post and then run a cable from the distribution post to the battery

Next you can run a positive cable from the fuse box to the distribution block or distribution post

The grounds

Run a new cable from the trans housing directly to the battery.

The next ground you can find a decent spot in the trunk (maybe strut tower) to run the second ground

If you do it this way you'll just have 2 cables (one +, one ground) running the length of the car

Or you can just skip the whole distribution block or post thing and run the starter cable directly to the battery and then run the fuse box cable directly to the battery as well.

And while your at it run a new power wire from the alternator to either the fuse box or from the alternator to the battery of from the fuse box to a distribution block...

And add a circuit breaker for the battery in the trunk somewhere


Make sense?