No, you can't add layout this way. You can set only existing layout.
Adding existing layout:
- adding in theme.xml
- adding in theme.php
- adding file with its name in layouts folder
Then you delete cache, check if you see it in theme manager... it has to work without any changes in jmtheme plugin (only header and footer is missing). Only then you can add (better is generate) new record for new layout.
It will be easier with new core version where layouts are just HTML files and you don't need to change theme.php