I just did it, and i got the shiny Dialga. :)
Now I have a nice collection of shinies, here they are :
Lugia, Ho-oh, Articuno, Zapdos, Suicune, Mewtwo, and Dialga. ^^
All Modest nature, full 31 IVs, and all caught in Premier Balls (The capture was the hardest part)
I'm gonna get a Heartgold Version so I can have Kyogre, Latias, Palkia and Giratina and complete my collection ^^