Installing new window channel is a chore akin to a monkey on a football, working in a tight space at awkward viewing angles and by feel. It's been decades since I did this last, so I'm a li'l fuzzy on the details. I was careful in removing the old channel, as it was mostly just a metal skeleton with little remnants of rubber. I'm not sure if what I did was the best way, but it worked, no adhesive needed.
This installation method is for doors with vent windows; I reckon full door glass would be similar.
•remove access panel and door glass for full access to channel track
•lay the rubber in the sun for an hour or so to get it more flexible
•install the new metal clip tabs into the door slots: horizontal tabs point towards the door latch, vertical tabs towards the running board
[I cheated here a tad by bending the tabs slightly so they were harder to install but less likely to pop out of the door slots]
•feed the new channel into door, either through the top or the access hole
•place the new rubber end against the vent window rubber and work the channel into the track by squeezing the opening together. I made a working tool out of some scrap plywood panel (about the thickness of the door glass) that was hand-width with a slight curve on the smoothed working edge to seat the channel into the guide evenly.
•while one hand is working the channel into the track, the other hand should be holding the remainder, and kinda applying a little pressure against the working direction so that the new rubber does not stretch.
•making the turn from horizontal to vertical becomes tricky as ya have to work the rubber in the window opening with one hand while supporting/pushing the remainder through the access hole with the other...gotta take your time here and work by feel.
•working the last few vertical inches is totally by feel since both hands are working through the access hole.
I think when I was done, the new channel was just shy of the end of the guide...either Roberts shipped me replacement rubber that was a tad shorter than original or I had put so much effort into keeping the replacement from stretching that it bunched up a li'l bit. Getting the replacement seated into the horizontal to vertical curve is critical so that the door glass will close properly. With new window channel installed, the door glass will be tight in the track; this is how I realized that my setting tape was faulty as the glass kept popping out of the regulator channel when the window was rolled down.
I do recall re-using some of the original clips as I broke a few of the new ones getting started. Getting that first one installed was a chore, but by the time I got to the 2nd, 3rd, 4th, it was not that hard with the tool I made, so there is a learning curve here.