pull
If your running it down the side of the car, as you should, then all the plastic is held on by clips... its getting it through the backseat thats the bitch...
but theres a guide on here on how to do that... do a search...
from the back of the headunit, just snake it through some stuff with other wires, down to the door, keeping it as hidden as possible, along the door, up to the back seat, through a hole to the boot...
done
good luck