Well, he does have grounds for appeal, since the judges instructions to the jury were faulty (see the opinion of an appeals court judge here). Looking at a summary of the court proceedings (here), a reasonable argument could be made that the prime perp was McClintic. She said so in court, and there was not really evidence to the contrary, so it should have been included in the instructions to the jury as a possible finding. So there is a point of law which needs to be clarified even if the effective outcome would be similar.
I am not sure what difference it would make though, since even if the court found McClintic as the primary mover, Rafferty would still be facing a life sentence anyway for his role. That is most likely the reason why legal aid groups are not interested in funding his appeals. Rafferty's motivation in pressing for the appeal is not to reduce the sentence, but rather make it possible for eventual parole someday, something that would be pretty unlikely if he is convicted as the primary mover in the case.
Well the grounds look pretty shaky but now I am curious as to whether PC is working on it. There has been nothing to indicate that he is and is being paid by the taxpayers to do so.
http://london.ctvnews.ca/polopoly_fs/1.1583513!/httpFile/file.pdf