I am in the process of doing the same on my K1200S from 2006. The seat has a big slit where your legs rest, and I bought a seat cover from Volcano in Italy.
I started pulling on the sides of the slit and the cover is actually glued but will separate from the foam, without damaging the shape of the foam.
I think the best way would be to install the cover on top of the existing/original cover if it is not damaged, but you would still have to pull all the staples on the underneath, so that you can nail new staples on top of your new cover.
Most of the glue is located on the edges, so it is easier to start pulling the old original cover from the middle of the seat, after cutting (if needed) a slit with a sharp blade.
Keep in mind that my seat is 17 years old and reacts in a certain way that your more recent seat may not do.
Yves
I started pulling on the sides of the slit and the cover is actually glued but will separate from the foam, without damaging the shape of the foam.
I think the best way would be to install the cover on top of the existing/original cover if it is not damaged, but you would still have to pull all the staples on the underneath, so that you can nail new staples on top of your new cover.
Most of the glue is located on the edges, so it is easier to start pulling the old original cover from the middle of the seat, after cutting (if needed) a slit with a sharp blade.
Keep in mind that my seat is 17 years old and reacts in a certain way that your more recent seat may not do.
Yves