unfortunately there is no documentation, this tutorial was user contributed. But you can use Free object to manage custom tables. It works in principle the same as any other object with one notable exception - there is no single item view yet. And if I remember correctly, to enable searches on it you will need to use code fields to insert a record into #__ckk_core table.
Thanks. I'm new to SEBLOD, so I'll look into this and ask questions when I run into issues. I have a lot to learn about SEBLOD. Looks like a lot of capability, but it would help if there was a lot more documentation, tutorials, and examples.