If you're doing this INSTEAD of eisinglas, that's exactly what you'd do - have panels made to slide in - but instead of clear vinyl, use a sun blocking material. Whoever you choose to make the panels will know what to do. If you have eisnglas, but don't ever use it - then either attach with snaps as mentioned, or just cut the vinyl out and sew in the fabric.
But you won't find this off-the-shelf - you'll need to go to a company to make them (or send mail the existing ones).