Redmine

I am building a web application that requires pulling certain issues from our Redmine repository. I can accomplish this by appending "issues.xml?key=<keyvalue>" to our Redmine URL. However, management would rather that the web page prompt the user for their Redmine username and password, and use that information to access Redmine issues.

Format I'm using now...
http://myredmine.com/issues.xml?key="1234567890123456789"

Assuming I have a web page with a login form (fields called "usernm" and "passwd), how do I form the URL to include the user login information?

Ron