Congrats!!!
Unfortunately, the only Shiny Mews that are really available belong to someone named Eppie and his stuff is nonredis :/ he used to take breeding projects so maybe you could do one for a trade. Karlmee had some too but I'm not sure about his activity...either of them actually, lol.
As for Jirachi, I don't know of any shiny ones that are legit...not that I can think of at the top anyways, ahaha.
Anyways, I'd most likely be back home for three days or so this coming week so I suppose we can do the trade then. Something to note, if you ever get over the pokesav aversion, Kazo has an amazing set of videos on youtube detailing how to rng on an emulator. It's much...much easier, lol. Towards the end of my career, I started doing emu abuse and it was super quick, lol.