Sparky,
I agree on installing the headliner before the steering column so there is a little more room to work.
The windshield channel weep tubes should be soldered into the lower outside part of the cab. They are ~3/16 copper tubes about 2-3 inches long. A short section of rubber line connects the weep tube to another ~3/16 copper tube that runs along the door hinge pillar exiting outside of the cab. I hope my description makes some sense.
