Finally I've found how to put xml or html tags in the CodeHighlighter. Post has to be escaped,

So convert ">" into "&gt;", "<" into "&lt;" and so on...

I have found also good online tool with which this is much easier to achieve:

If I am writing Joomla! article without any text editor and if I want to show ";gt;", then I should write it like "&amp;gt;" :)