to thread the loom i used a length of twin and earth house main wiring as its flexible enough to bend but stiff enough to go straight down the chassis without bunching up, then when it gets to the other end, pull it through the hole (may take a bit of effort) and i worked front to back as it seemed easier. once its through the hole, make sure the loom is well protected and fix the loom to the piece of wire you origionally threaded, then just simply and CAREFULLY pull the loom through the chassis. job done.