I am not 100% sure of access points on your boat, but typically if you start at the box, the wires will need to be run through the helm, from there down the wire chase and then accessed somewhere from the cabin, possibly from behind the head or in that vacinity and that will give you access to the wire runs under the deck, you can use the in deck circular inspection hatches to run the wire from location to location, typically you will need to run the wires outboard from the helm wire chase to get access to under the companion seats. There should be an access port in or near that bulkhead as well. I recommend using a wire puller/creep stick.
http://www.mcmelectronics.com/product/2 ... =240969538
It will allow you to easily run the wire from access point to access point, and also aids in running wires down the helm wire chase if you have a lot of wires run and it is a tight fit.
You might have to do a little peaking around and open each access hatch to see how to run the wires, looking at your owners manual and how the wire diagram's run wire's will also help give you some input into the exact way to run these wires. You should have access to get to this location without a problem, just need to put in a little time to search out the exact route. If you have 2 guys, it makes life a lot easier to poke around and run the wire's, but the creep stick will allow you to do it alone, without a creep stick you will have difficulty running wire's, they will want to curl and might make running them a pita. Good luck, hopefully this helps get you started and maybe someone with your model can chime in with more details.