Illegal aliens and social security

John McCain has recently complained that a Mitt Romney ad was misleading about his record in regards to illegal aliens receiving Social Security benefits. From the ad, as discussed on Fox News Sunday ( http://www.foxnews.com/story/0,2933,320520,00.html ):

McCain pushed to let every illegal immigrant stay here permanently. He even voted to allow illegals to collect Social Security.
As Chris Wallace points out, that's misleading. However, it's only misleading in the temporal sense, and the ad should have said something like:

"McCain would wave a magic wand, rapidly convert millions of former illegal aliens into legal workers with a massive amnesty, and then give them Social Security benefits."
Kaus' rounds up the effects of the McCain-Kennedy scheme here:
http://www.slate.com/id/2181118/#grufftesty

illegals wouldn't have to pay fines and wait to become citizens to get Social Security. They'd qualify for Social Security almost immediately, as soon has they got their quickie "probationary" Z-visas. But most might not get credit for earlier work done here illegally, at least immediately. That depends on whether you're talking about the 2006 McCain or the 2007 McCain.
He also has a long excerpt from an email Mark Krikorian sent him with the details; he also briefly mentions the separate issue of the Mexico-U.S. Totalization Agreement: http://lonewacko.com/blog/archives/006078.html
http://lonewacko.com/blog/archives/007375.html