I personally don't know if the keys can be updated without upgrading the whole PS3 software. But unless you are staying on 3.41 for a specific reason, you may just want to upgrade to one of the 3.55cfw's.
From my experience, the 3.55kmeaw cfw (just using that one as a reference as I didn't use the others) did everything the 3.41 with hermes dongle did. But even with 3.55 there will still be an issue with the keys needing updating at some point. At least if you update to one of the 3.55s it should help with some blu-ray movies. If someone does know how to update the keys, I would also love to know how it's done.