Sorry I can't help with your exact question, but I am also looking into the MRT spoiler as well. I sent them an e-mail asking if it would fit the 2002 wrx and they said this.
We can certainly supply the 22B replica wing (with adjustable centre downforce section) to suit your MY02 model ... The wings fit the standard mounting points as used by the standard wing, and are supplied complete with a rear LED brake light as well.
They did not mention anything about other holes. Even if there were other holes needed I don't think they would be entirely neccesary unless you plan on driving at high speeds (>90 mph) for long periods of time such as on a track.
Also on a side note, if the currency convertor on their page is correct this 22B adjustable replica only costs 350 dollars unpainted, and I would assume shipping would be around 100, so 450 total. I e-mailed one of the MRT vendors in America and they quoted me 550, seems like they are making a large profit off these. You might want to look into that.
Anyways, if anyone has any other info please let us know.