Here is a great video from a custom showing the install of the sunroof seal.
Procedure:
1. Remove the sunroof from the car and place it somewhere safe.
2. Remove a little section of the old seal (12 inches), and then install the new seal in it’s place. Then remove another section of the old seal, and push on more of the new seal. Continue all the way around until you have the new seal on.
3. Since the seal is rubber, it can be stretched or compressed while installing it. This will make the seal seem either too long, or too short, but can easily be fixed.
If the seal seems too short, try removing some of the seal and stretching it ever so slightly while installing it, then it should fit perfectly.
If the seal seems too long then it was being stretched a little while being installed. Remove anywhere from 12 inches to one whole side of the seal from the car. Then install the seal in the middle first, and then work your way to each end. remembering to push the seal straight down when installing it, as to not stretch or compress the seal. The pictures below are an example of how to fix this.
If your seal looks like this, then it was stretched a little while installing it. Remove some of the seal from the car and start in the middle when installing it.
Here we removed about 12 inches of the seal from the car, then pressed down in the center, making 2 smaller humps. Then you can easily press the rest of the seal straight on.