I don't know how easy that would be -- don't know how easy its considerably more potent chips it used are to come by these days (think they were largely searching for old stock for some of the later batches and + line, and onesy-twosy someone has to do a one off replacement with does not make a batch), and I am not aware of any kits being sold for it (granted dsone was also similarly absent and we have that). Best (other than someone making a compatible version from scratch) would be if someone leaked the iplayer and ismart mm (iplayer was supercard trying a non piracy device, they sold the kit on to ismart* who ported a slightly older version of the dstwo eos to it, were restricted from doing anything much for homebrew though so it got a version of dingux and not much else, said dingux later being ported to the DStwo which is what people use to play Amiga, PS1 at borderline slideshow and whatever else that native homebrew could only dream of, and corrupt their flash cart when they turn off without shutting down properly).
*one of the then bigger flash cart vendors thought they would try their hand at it. It died when the owner did though, a few ex employees bought the remaining stock (which also included ismart's ismartds which was an EZ5 licensed version) and sold those on and that was the end of that for the most part. Never saw an source code or knew if they had access to specs.
Oh yeah forgot to mention last time the DSTwo (and other enhanced flash carts) gobble a bit more power than a conventional flash cart, and will even if you are playing stock DS games.