How to become a Technical Writer?

The best part of my IT job is when I have the chance to do software and training documentation (user guides, FAQs, step-by-step instructions, etc.). I enjoy it so much that I’d like to do it full time…without having to go back to school for 2-4 years for a piece of paper saying I’m qualified to do it.

In your opinion/experience do you think it is possible for someone to break into the technical writing profession without having a BA or diploma in the subject? Would you hire someone with a good portfolio, a few years of experience and only a few courses in technical writing? Do you have any advice for making this possible?

Thanks!