It should work but you will need to know your parameters first before trying to Rng an ID because you need to input the seed with the pid that you want to become shiny. Here's a guide written my bond697, just scroll down the page until you find ID abuse information :). Both mine and my older brothers retail black games are c7c on two different ds's. I got myself a supercard dstwo flashcard so that I didn't have to restart my retail black and white games :P.
If you want to find the parameters for a flashcard you will need to adjust the parameter search, vcount should be changed to 0-80, timer0 needs to be changed to 700-8ff, gxstat stays at 6, vframe should be 0-19 and the seconds should be synched with an external clock. That's all the stuff that I needed to do to find the parameters for my supercard dstwo so it may be different with another flashcard.