I am trying to get a \ into the text area but nothing seems to work.
From what I can find, the code is 005C for a \

I have tried /u005C and \u005C but neither give the \

Am I doing something wrong or is there no way to use the \?

Just escape it with \, so it'd be \\. In JSON (what plugin config files use), \ is a character used for escaping generally.

Doing that really messes it up. When I click on the tab button to show the tab, the tab button disappears and so does some other tab buttons randomly and the tab is blank.