I don't think you know what you're talking about. Carnitas is made by covering pork (usually butt cuts) with a liquid - can be melted lard or even water and simmering until the pork is fork tender, then you turn up the heat and brown until crisp. How would you even be able to tell "par-boiled" Ridiculous
Here is a recipe from Rick Bayless - Renowned Mexican chef
He uses country style pork ribs
The boil-then-fry method: Place the meat in a single layer in a wide, heavy saucepan, add enough water to cover the meat by 1/2-inch, measure in the salt, and set over medium heat. Simmer, partially covered, turning the pork occasionally, until the meat is barely tender, about 40 minutes. Uncover, raise the heat to medium-high, and quickly boil away the liquid.
When you hear the meat begin to fry in its own rendered lard (once the water is gone), turn the heat down to between medium and medium-low. Let the pork fry, turning frequently, until evenly browned, about 30 minutes. Remove the ribs from the pan, drain on paper towels, and sprinkle with a little salt. Cut into bite-size pieces or shred with fork.