Whenever I dropped into Plato Rhyne's office to forward a reccomendation, he just wanted to briefly talk about the pilot, if I've flown with him and get his SSN number to flag his application in the UPAS database.
Once he got flagged, in general he got a phone call a few weeks later for the interview.
Pretty simple process, involved no cover letters not even a resume.
When I got my pal Joe hired at Skyway, I went into the chief pilots office during one of his tirades about not being able to find pilots, dialed Joe's number and handed the chief pilot the telephone and said, "It's 5:40AM in California, he won't mind, talk to him".
There is absolutely no better way of getting an interview than having a company pilot you personally know and have flown with physically walk-in your resume to the person in charge of pilot selection.
Works better than career services, seminars, presentations, conventions, etc. And it's free! Well, if you don't bribe the guy with a 12-pack of Labatt's Blue Label.