e.g. you can put this in the very top of your org file:
#+TODO: TODO IN-PROGRESS WAITING DONE
and when you open in Emacs, now you have 4 states, TODO, IN-PROGRESS, WAITING, and DONE
However, opening the document in beorg only shows TODO and DONE, the two default states.
Likewise, you can put this in your .emacs file:
(setq org-todo-keywords '((sequence "TODO" "IN-PROGRESS" "WAITING" "DONE")))
and those four are now the default states for all org files.
Never mind, figured it out. beorg does not detect this, but can be modified to use it.
In beorg, go to Settings, scroll down to TODO / Action States
Enter the states, separated by a space and comma, like this:
TODO, IN-PROGRESS, WAITING
(DONE is under "Done States" already)
I'm hoping to support per-file states at some point in the future. In addition to the Settings tab you can also create a beorg init.org and configure the states in a similar way to Emacs.