[wp-hackers] Use WP as an authentication system

[Alex Hempton-Smith]

Hi all,
I'm building a set of custom apps/scripts for our charity and I would like
to make these available at "staff.example.com". I have a regular install of
WP in "example.com/wp/". The staff subdomain's content is actually in /home/
example.com/staff/.

Instead of re-invent the wheel I (and to have the same usernames/passwords),
I would like to use the authentication system from the WP install on my own
custom PHP stuff in the subdomain. And then be able to use normal WP
functions within my own app, like checking if they're logged in, getting
usernames etc.

What do I need to do to allow my users to log into the main install, and
then be logged into the custom area?

I know it'll be more than just including 'wp-blog-header.php', because of
cookies etc?

Many thanks if anyone can help!

-- Alex