How can it be done to make Rick Santorum the Republican for 2012??? He is a very poor candidate and socially conservative but he appealed to a small religious base that was anti-Romney. He does not need to win and is likely to lose badly though.
Run a Trump-lite campaign. Honestly he would probably get a lot of the folks that OTL went for Trump in the primaries in 2016. He's floated similar ideas in the past. The problem is that, policies aside, Santorum is just well, another suit. He doesn't have Trump's (stated) business credentials (no, financing indie films does not fucking count) and frankly, his personal life is just boring, which is a good thing after the election, but not before. I suppose if the establishment fractures like OTL 2016 he might squeak through.
As for the general, well, like Trump, Santorum, if he manages to win the nomination, is unlikely to run as a conventional Republican. Of course, some thinfs will be of course different - the Religious Right isn't likely to waver over a man who has nuns squeeing over him. However, unlike 2016, Obama has the incumbency advantage. My prediction is Obama wins in roughly comparable results, and the Republican Party gets a 3 cornered internal faction fight between the Old Guard, the Santorum types and the nationalists.