Generating codeigniter user_guide like documentation

[eluser]kakawett[/eluser]
It's been a few months since I started one of my project and I just figured out a lot of code I wrote back there are just not understandable so I'd like to generate my own userguide, which would looks like the code igniter's one (same syntax, same style, same way of browsing etc...) to describe my features in case I re-work on them later.

Is it possible ? how do I do that ? Otherwise, is there a good way to generate documentation for PHP code ? if possible through comments

[eluser]Brandon Beasley[/eluser]
The design elements are included in the user guide:

Codeigniter Style Sheet and Page Template

[eluser]kakawett[/eluser]
Thanks.