Thanks to Kaphotics, OmegaDonut and others who have done great research into WISHMKR jirachi. We are ready for the moment of truth. I have a SAVE file which I have constructed in such a brilliant way that it will generate a shiny jirachi when one is received.
I urge EVERYONE to try this and get back to me on whether they got one. I don't have a link cable so I cannot test this
The seeds should be:
Shiny - 353D
NonShiny - 353E
I would also like to thank loadingNOW for his research into the GBA games.