Create external Piwik Account after registration

Hey guys,

i got two systems running on my server: Drupal and Piwik (open source statistik tool). The main system is drupal and i integrated some Piwik Featues into the user-accounts via the Piwik API. This works really fine.

Now i want to automate the registration process: When a user account in Drupal got created a Piwik-account should be created too. The returned authentification_token at registration in piwik should be stored in the personal user profile - There is a hidden drupal profile field which is called profile_piwiktoken.

I found the tutorial 7 - http://drupal.org/node/632140 - but just don't know how to start.

The API call to add the user is:

http://domain.com/piwik/?module=API&method=UsersManager.addUser&userLogi...''&format=PHP&prettyDisplay=true&token_auth=admintoken12345

--> UsersManager.addUser (userLogin, password, email, alias = '')

This outputs following code:
a:2:{s:6:"result";s:7:"success";s:7:"message";s:2:"ok";}

After that I can generate the personal user token:
API-Call:

http://domain.com/piwik/?module=API&method=UsersManager.getTokenAuth&use...

--> UsersManager.getTokenAuth (userLogin, md5Password)

This outputs the personal token:

s:32:"8af9abab49907995f9c1839091380915";

Can anyone give me a hint how to call this API and save the value in the user profile? This would be great.

Thanks

Stefan