Currently Recovery Media does not support serial consoles. Does CLI interface work by the way? If it does then please use it to perform restores. If it does not work then you might want to stick with the following workaround:
1. Run Debian Livecd that supports serial console and install VAL there.
2. Use CLI to perform restore operation (please refer to the user guide or man veeamconfig for directions.
You're not the only person to use VAL with serial console, so I consider you post as a feature request. Thanks for sharing!