From http://www.seriouseats.com/2011/12/the-food-lab-how-to-make-all-belly-porchetta-the-ultimate-holiday-roast-italian-roast-pork.html. The only two changes are (1) add more garlic, (2) cook way longer. He says 4 hours, I say 7 (including time on high heat to blister the skin). The other tip is to coarsely hack up the meat and skin and serve in banh mi style sandwiches (french roll, cilantro, and carrot/daikon/rice-wine-vinegar pickle). The sandwiches are epic.
that looks just amazing. way to continually raise the bar!