Unsually by joinning professional organizations and getting to know them outside of the work environment first. Or otherwise, finding out their names by doing a little detective work and contacting them directly - many will be frustrated with their HR Departments' incompetence and willing to look at your resume first themselves. ;)
I work in HR. I'd like to think I'm not incompetent. My job is to get the best person for the job, matching the applicants job skills with company culture (sometimes the most qualified person isn't the best fit for the job, if that makes sense).
Honestly, most of the resumes I see are crap. Applicants get really frustrated at HR, but sometimes they need to take an honest look at how they are selling themselves. No one in HR has the time to read each resume line by line. Also, most resumes are being put in a data bank. We do lots of keyword searches. If you don't put the correct lingo in tyour resume, then we aren't going to call you.
I will admit - there are incompetent people in HR. But sometimes applicants do a horrible job of selling themselves. I really get tired with hearing how I'm incompetent because Joe can't write a resume.