Alberto Rivera was a fraud. He was never a Catholic bishop, never a Jesuit, and never a priest. He may have attended a seminary at one point, but that's it.
I'll grant you that he was a real person, and probably a practicing Catholic layman at some point.
Christianity Today, an evangelical magazine, completely debunked Rivera's story a few years ago. He's a phony, and his claims are lies.
I had wondered as much. Rivera's role as an informant/witness reminded me unconfortably of former Christian author and comedian Mike Warnke. Warnke claimed to be a converted Satanist in his book The Satan Seller, but was ultimately outed as merely an opportunist who concocted his tale for profit.
http://members.tripod.com/~dabz_2/updates/critics/critics.htm
Sorry, but I haven't learned linking yet. You'll have to copy/paste.