It is possible to do management of users & group membership outside of the Servoy Security Tool, and to implement your own login form. I have posted to my website an article that describes how to do this. The article also explains how to use my free McGilly_security module that instantly adds basic user & group management and login functionality to any solution. You can use this module as a starting point and customize further as needed.
This link is broken. Is it possible to make it available again?
Cheers,