how can I protect my project by using htaccess

[eluser]Unknown[/eluser]
Hi all,
I want to ask about http authentication in CI.
Here is my project structure:

my_project
.htaccess
index.php
-- system
-- application
---- controllers
------------- default.php
------------- demo.php
...
---- models
---- views
...

Now, I want to protect my_project by using htaccess (example: user1/pass1), and for the Demo controller (demo.php), I want to protect by other pass (ex: user2/pass2)
Please let me know how do I do this?
Thanks.