To keep this strictly for SL authenticated users you can only sign up in world. You may only do a password reset, in world. No personal info is required, not even your email address.
Here is a link to the Marketplace (CLICK HERE) where you can grab the free HUD that allows you to register. Add the hud, watch your nearby chat for login details… Click the screen. Click the black frame around the HUD to register. Detach. If you need to reset your password just add it again, click the black frame area.
NOTE: To activate your account you must log in, so why not log in right away & set your password to something you’ll remember? Add some friends. Contact Cygnostik Flux for inquiries.