On the computer but to be honest this isn't a "pretty" method so if you don't have some understanding of what that batch file is doing I would suggest you leave it alone until someone puts a proper guide together. Messing this up will likely leave you with a very expensive paperweight (brick your phone.)
Now that a confirmed method is out there it's only a matter of time before someone wraps it up in a noob friendly package. Just hang tight until then.