You can sign up for the Beta testing program online at www.topazlabs.com/forum
Once you create an account:
Go to Settings -> Permission Groups and select the Beta group and enter you system info there to apply. Once approved you will see a new Beta testing forum when you log in.
Because we maintain a limited number of beta testers, we may temporarily stop accepting requests at times. See here for additional assistance on signing up for the beta program: How to Become a Topaz Beta Tester