If you do, Jesse Liberty has some excellent advice for you on his blog. It’s never too late to get started. And yes, it can be done on your own. (With some help from books, online info and people, and lots of resolve.)

From his entry:

And that is what I’d suggest you do; learn a lot less than there is to learn; narrow the field. Start by getting opinions from people who seem to love their jobs and who actually code for a living. Note that none of us will be right, but you may be able to eliminate some areas that are clearly wrong. Then pick a narrow field and learn that and nothing else for the first year.

Jesse points out a few areas on which to focus, then describes a method of attack.