Applied through usajobs and received an email to schedule an interview about a month later. The process consisted of going to their headquarters, listening to HR people tell you about the job and ask if you're still interested or have questions, sign a few more forms, take a color vision test, interview, get fingerprinted, and at the very end get told if you were hired or not and if so it was based on a successful background check.
There's a huge problem when applying for this job however: Even if you do pass a background check, which I did, that doesn't mean you will start working. You only work IF there's positions available, so I NEVER received a phone call for starting/training. Plus there's a 6 month time limit on your background check as well, meaning you will have to apply and interview over and over just for the chance to work this low paying job.