"Corning" is an Olde English term and refers to preserving of the brisket in a brine using 'corns' of salt and water. In early parlance, most large granular material (like the salt used) was referred to individually as 'corns'. The process is as old as butchering, with as many imagined variations. Brining beef with salt alone generally turns it a greyish color. Spices are added to impart more flavor and color. In many cases, the spice list includes sugar, saltpeter, cinnamon, mustard seeds, peppercorns, cloves, allspice, juniper berries, bay leaves, garlic and ginger. As you can readily see - a good pickle recipe will go far toward creating an excellent corned beef.
You should allow at least 5 days of soaking in the brine (10 would be better), so if you want your own corned beef brisket for March 17, you need to start just about now.
The longhand version (Food Network's Alton Brown) of making corned beef brisket can be found at this link.