CKEDITOR.config.disableReadonlyStyling

I don't find it in documentation

I need to insert personnal tags in my text;
exemple : <diaporama10> or <gallery|id=10> for Spip CMS

But CKEditor cancel these tags

I suppose, it will be possible with CKEDITOR.config.disableReadonlyStyling, but no documentation and exemple

How to insert personnal tags

Thank you