I found this in the early911sregistry forum.
https://www.early911sregistry.org/forums/showthread.php?98900-Pop-out-1-4-panel-window-seal-help-needed&highlight=quarter+window+seal+replacement
Soak the seal in hot water for ~10 min to make it more pliable. Use Windex and spray the inner part of the seal. Apply pressure to snap the seal into the track of the window trim/frame. I will try this method and report back.