You could try doing volunteer work with a historical society as a docent at a historical house or museum. You could also even apply as a tour guide at some historical site. Even as a volunteer, you would eventually know enough about the place to get promoted. Once you've broken into the field and surrounded yourself with like-minded people, try to make connections with people who do what you think you would enjoy doing for a living.

In addition to the above, you might also try doing serious research and beginning to publish serious articles--once you've accumulated a decent-sized body of work, that might be used as a foot in the door somewhere.