You MUST disconnect the battery before removing the pillar (airbags)!
The pillar takes two motions to get off. First, pull back the weather stripping in the door (not off the door). Then unclip the plastic a little at a time, note that it will still be hooked the the pillar, so just unsnap it. To unhook the plastic cover, pull up towards the headliner. There are basically plastic "hooks" built into the pillar.
When running your cabling make sure you do not obstruct the airbags or interfere with the path of deployment.