hotspot - external login page

Hi there,
I’ve been reading the wiki on the hotspot external login page but I’m at a bit of a loss at the moment on how to get it to work.

What I would like to do is centralise a login page (so only 1 page needs to be updated rather than every NAS) and have all users try and log in using this page which is hosted on an external server.
so: RB > Hotspot login > external re-direct to webpage > external host of login page > Return results to RB.

I should also mention that I do use an external Radius server to authorise users, which is held on another server from where my login page will be.

Once I can get the basic page working, I’d like to it working with Joomla so everything is updated inline with the webpage.

before asking you could have done a bit google or search here
any ways have a look at
http://wiki.mikrotik.com/wiki/HotSpot_external_login_page

and don’t forget to give karma if this helped