Regarding the scenario you are describing, if the issue is that users have to re-authenticate for every web application on the server, you would be better of implementing SSO/Session based authentication on the server then coding this workaround. With Session based authentication, users only have to authenticate once.
From the admin help:
Session-based name-and-password authentication sends the client's name and unencrypted password, and is sent with each request to the server. Session-based authentication differs in that the user's name and password information is sent over the network only the first time the user logs in to a server, not each time a request is posted. After login, the user's name and logon information is stored in a cookie in the user's browswer, and the browser sends the cookie to the server with each request. Before honoring a request, the server verifies the information in the cookie and uses the cookie contents to identify the logged-in user. The session is only valid within the browser in which the login was performed. If the user shuts down the browser in which the session login took place, the user's session will be ended and the cookie will be destroyed.
Using session-based name-and-password authentication provides greater control over user interaction than basic name-and-password authentication. For example, you can customize the form in which users enter their name and password information. It also allows users to log out of the session without closing the browser.
If you are using windows based servers, you could even implement SPNEGO, automatically signing the users in using der Windows account, therefore eliminating login prompts completely.
With Domino 9, you also have the option of using Security Assertion Markup Language (SAML) to configure federated-identity authentication.
In your case, I would start with Session-based name-and-password authentication to solve the multiple-login issue.