You can pop the old seals out with a screwdriver or something else to pry them out. Just be cautious you don’t score or damage the inside of the fork leg/lower.
First make sure the fork lowers are clean.
Then sit the fork seals flat onto the top of the fork tube. It helps if you have a large socket, or something similar to help drive them in. I happen to have a 36mm socket that fits the diameter of the seal pretty good. It might be better if it was 34 or 35mm but it still did the trick.
I placed the socket over the seal, and tapped it in with a hammer. Here is a photo of the job with the seals about half way in:
Here are the two fork lowers with the seals fully inserted: