Hi Jamie,
I am 99% certain that the info you’ve found in the osTicket docs pertain only to 1.11-RC1 (for now). Unfortunately the Docs do not specify this, so your confusion is only natural. And just to be certain I have asked for clarification.
I do not plan to release a version of osTicket for 1.11RCx as RC versions are not recommended in production environments.
Others have asked about using custom code to implement their own custom columns in osTicket 1.10.x. I can tell you that this is possible, but it will not work well with osTicket Awesome.
My best advice it to wait, if you can, for the release of osTicket 1.11-FINAL. Shortly thereafter I will released an updated osTicket Awesome that will fully support the new Custom Columns. Which will be an amazing new feature by-the-way!
I hope this answers your question, but feel free to let me know if I’ve missed something.