The answer may be easier than you think, but there's a catch.
The truth is that you find a telecommute job just like you find any other job- with research, persistence and a bit of job search savvy.
The caveat? Ever wonder why more companies don't advertise telecommute jobs? In this competitive job market you'd think more of them would see the benefits of hiring telecommuters. Well, many of them do, they just don't advertise their telecommute positions. The sad fact is that when they do, they are inundated with responses from applicants who aren't remotely qualified for the position. There seems to be a persistent rumor circulating that the desire to work at home somehow qualifies a person to perform a job. This has really turned employers off to posting telecommute positions for the world to see.
With that said, you can see how important it is to be very realistic when applying for a telecommute position. Think of your home-based job search as a "traditional" job search. Keep in mind that many companies are telecommute friendly, even if they don't list that in their job listing or ad. In fact, the company you are currently working for may be willing to allow partial telecommuting. That should be the first place you look. Many companies are testing the waters by allowing employees to work from home on a part-time basis.
If you feel that this is a possibility for your company, the first thing you should do is determine whether or not the job you do is appropriate for telecommuting. If you are a receptionist who does clerical and phone work, then your job could possibly be performed from home, but if you also greet clients then it may not be an option. Here is a good article on how to convince your boss to let you telecommute.
For an external job search, definitely check out the sites that cater to telecommuters. Some good sites are
About.com, Gil Gordon's site, and Dice.com. Aside from that, you should identify companies that you want to work for and apply to them. You will find a listing of Telecommute Friendly Companies here at 2Work-At-Home.com.