If you're in an area where tech employees are in high demand, like Silicon Valley or New York, you'll be in a better position to make this transition. You've got to hit things just right, as Legate acknowledges. He already had experience in networking and systems administration, from summer jobs and consulting work. If this had been two years earlier, maybe I wouldn't have been as lucky as I've been. If you're just out of high school, or have just a year or two of college, employers may be wary, thinking you may not have the maturity for the job.
References help, as does previous experience in the IT world.
Use your resume and interviews to demonstrate your maturity, detailing projects you've worked on to completion, how you've worked as part of team, and anything else to assure an employer you're responsible and able to work with others. Experience, any way you can get it. Without a degree, experience is essential. Legate credits his ability to enter the IT workforce at such a young age to that combination of expertise and contacts. He got his break when a former boss called him and offered him a job at AboveNet , leading to a full-time job for the company.