how do i cook pork center cut loin filet?!

You have a very, very lean cut of meat. It'll dry out badly if you try to broil or fry it. The slow cooker would be best based on your post; let it cook slowly and with moisture such as broth and wine to keep it from drying out. Being preseasoned, I'd forgo any spices, but it'd still put a layer of sliced onions under it so it's not sitting flat on the bottom of the pot. I'd cook it on low for 6 - 8 hours, depending on the weight, with the sliced onions underneath and the liquid about 1/3 of the way up the side of the roast. Of course, let it rest before slicing.