The press' love for McCain seems likely to be as big a factor as we thought it would be.  I think the only way there's a chance of the press adopting anything like neutrality is if Obama personally distinguishes between McCain's war heroism and the ability to make good policy decisions.  I suggest this refrain:

"John McCain is a war hero, and I honor his service, but he has made one disastrous decision after another about the war in Iraq. 

"John McCain is a war hero, and I honor his service, but he wants to keep American troops in Iraq until the Iraqis stop shooting at each other and at our troops.  And after that happens - however long that takes - he's fine with keeping our troops there for another 100 years on top of that.

"John McCain is a war hero, and I honor his service, but he has flip-flopped on whether we should be torturing people:  first declaring his opposition to it, and then voting against legislation that would repudiate George W. Bush's embrace of torture.

"John McCain is a war hero, and I honor his service, but for economic advice he turns to Phil Gramm -- the man who engineered the reckless deregulation of financial markets that has helped to create the economic problems we are living with now, including high gas prices."

And so on. 

I think Obama should use the phrase "John McCain is a war hero, and I honor his service, but..." so often that (a) the relevance of heroism is sharply and obviously limited (b) it is clear that Obama cannot be painted as being unfairly critical, and (c) people lose interest in hearing about war heroism.

I don't think this should be left to surrogates, and I don't think Obama can rely on the press to see the obvious.  Unless Obama personally drives the point home forcefully and repeatedly, the press will continue acting as surrogates for McCain, pretending that "war hero" necessarily translates into "good president" and that any questioning of that equation is an act of slander.