TinyMCE adding dynamic custom tags

Question

Im trying to switch to TinyMCE from CKEDITOR and I need to be able to write in the source custom dynamic tags... eg: hightlight-123 where the highlight- is static but the number changes... I looked in the TinyMCE docs but couldn't find any way to add custom elements with a regex or starting with a string.

how can I change my configuration to allow custom tags with some sort of regex?

here is the relevant part of my tinyMCE config:

 {
extended_valid_elements: 'highlight[style]',
        custom_elements: 'highlight'
}