90 GT vert, changing retainer channel to frame seal

Someone please help, I haven't done any weatherstripping work on a convertible before and I need some info. I want to change the "retainer channel to frame" seal on my triple black 90 GT vert, but don't know how big a job it is, what needs to be pulled off and how, etc.

I also need to have my car done for the Car Craft Summer cruise which is next weekend already. Please help ASAP! Thanks in advance, people.