I first straighten the channel. I don't know why the manufacturers bend them in the opposite direction. Maybe they naturally bend in that direction without kinking.
I then insert one end into the rear of the door until it engages with the doohickey at the bottom of the door channel. The extra length will go straight up in the air outside of the window opening.
I then carefully make the first bend to fit the radius of rear of the door. The long end of the channel will extend past the front of the cab.
I then carefully make the second bend to fit the radius of the front of the door. This can be done without inserting the channel inside of the door. it can hang outside of the window opening.
I then remove the channel from the door, then install it by inserting both ends into the door channels.
Don't worry about engaging the front end into the doohickey at the bottom of the front door channel. Allow it to go past the end of the door channel at this time, as it will need to be cut to length later.
Now roll the window up to aid in forming the channel to fit the glass. The cornes will have some kinks which can be worked into place with wide screw driver.
Once the channel fits the glass with the window all the way up you can mark the front end of the channel to cut to the proper length and insert it into the doohickey at the bottom of the door channel.
