Accessing the cab side of the door jamb

[davepl]

I'd like to install some contact switches to pass along lines for (hidden) power windows or power locks. I have the contact switches, as I'd rather not run a conduit.

Seems simple enough, but where can I get good access to the back side of the cab's door jamb, about where the dome light switch currently is?

I'm wondering if you can reach through the vent and get there, or if there's some way to get at the back side of it. Other than the factory door jamb switch there's nothing in there, so I never have had occasion to be in there!

Thanks,
Dave