A few videos I saw stated you can now either do this with a random encounter shiny OR chained ones. For Pearl I decided to try both and see if it resulted in the same SID. So last night I went into LV 100 battles with myself over wi-fi to get the stats of my random enounter geodude from pearl and a bunch of chained shinies from the same game. This morning I used the RNG Reporter to find out their IVs. The random encounter Geodude gave me an SID number, so then I decided to double check with the chained shinies and sure enough, after a lot of fiddling around, they too, gave me the exact same number.
So then I went through the steps to actually generate the egg (635 happiness checker taps arrrgh) and then went to hatch my egg to see if it was shiny or not, fully expecting that i screwed up somewhere and it wouldn't hatch shiny.
I have a shiny Finneon now, omg yaaay ;w;
Part of me feels bad for manipulating the game like that but at the same time, I can now breed any shiny I want on Pearl which makes my dreams of having a shiny dex so much more realistic! (Plus getting some fav shinies that are otherwise really hard to get)