restful_authentication with web services


i have a question about using rails 1.2 for restful web services. with the new features, it's really easy to get the results in xml. however, i am struggling to have a login system to authenticate the user. i am trying to utilize restful_authentication for the task. but i am unable to find documentation on how to use the plugin with xml. furthermore, once the user is authenticated, i was thinking about keeping the person logged in by passing a token. however, i don't know how to do that with restful_authentication as well. is there another plugin i should look at? any help/directions would be much appreciated.