I have no idea about your specific unit. If you have batt type insulation in the ceiling, you can run wiring around. If you have a pancake/dome light in the area, if you temporarily remove it, you will find about a 1" dia. hole that can be used for fishing wires (have done this). If you have a fan, vent, speaker, etc. in the area, removing them can provide access to the ceiling. If you absolutely must, you can use an electrical cover plate to cover up an access hole you need to make.
If you are able to work out an access path in the ceiling from one end to the other, if you use a nylon fish tape (Harbor Freight has them) you can work the tape from one end to the other and then pull your cable through. Can take some time and patience to feed the fish tape through where you need to.
Not sure if this is of any help or not. If not, just toss it away....
Gil & Deb & Dougal the Springer Spaniel
2014 KZ Spree 262RKS & Ford F250 supercab V10 4x4 LB