This should allow a seamless migration from WP-Updates.com to Kernl.us. This hasn't been tested yet, but I'll give it a try this week sometime and write up some documentation.
- Remove wp-updates code from your plugin/theme.
- Add Kernl update code to your plugin/theme.
- Upload this new version to Kernl as your initial plugin.
- Upload this new version to wp-updates.
- This should redirect all end-users to Kernl for updates seamlessly.