Step-by-step indicator gasket install wanted

I've seen comments on this site indicating that trying to install the front indicator light gaskets for a Euro Dino can be `challenging'. My gaskets are on order and I was wondering what the step-by-step procedure was for installing them. I assume that only the lens cover needs to be removed prior to installation and not the entire light assembly, correct?

I anticipate the challenge of installation given that the lens covers are very, very tight up against the body olong the bottom edge with no obvious issues expected along the top (decent gap there). Am I fooling myself?

Any suggestions on how to make this install go smoothly