You can do it in two places:
1. Go to Proxioshowcase.com Click "login to my account" button at the top, add your email address and password (or your username and password from ProxioPro.com) then click Login
2. Go to ProxioPro.com, add your username and password then click "Log In"
Once logged In, just Click the "Proxio Developer Showcase" button and this will take you to your Agent's Dashboard.