Google Wave now supports robots that run on non-App Engine domains. To use a robot on your own domain, you must register it to obtain a consumer key and secret that you can specify in your code. At this time, non-App Engine robots can only run on WaveSandbox.com. In the future, they will be enabled on Wave Preview.
The 3-step registration process is shown below:
To get started, visit the registration page for WaveSandbox.com.
Create a static file or servlet at the given URL that contains the verification token.
Store the consumer key and secret in a credentials file, and use them to setup Oauth for your robot before sending operations.