Then again, I've known some serious dipshits that have gotten some nice jobs with contracting companies to work with the DoD on various projects.
Helps a ton if you have .gov security clearance. Sometimes it's easier to put in a dip@#$ who has an existing clearance than go in and wait up to two years and $120,000 for a background check and put a qualified person in.
checks in the mail...Good advice already.
Matefrio is right, either through audit or as a system admin. Like MM said CISSP is the main cert.
You may also want to read up on some of the common authoritative sources ISO27001/2, HITEC, NIST, etc. just to become familiar with what's in them at a high level. That way you can at least speak to them in an interview.
Or...ask to help with SOX; people will gladly let you
DISCLAIMER: I'm not a day-to-day security guy so take my advice for what you paid for it.