Regex for URL group needed

I need a negative rule
basic idea is:
.*domain.com/blog/.+
> block every path which is longer then ".*domain.com/blog/" like ".*domain.com/blog/category"
then I need to add some exceptions like:
.*domain.com/blog/(!?except/slug/.+).+
> block every path which is longer then ".*domain.com/blog/" like ".*domain.com/blog/category"
> except when the path looks like e.g. ".*domain.com/except/slug/not-blocked"
but the (!?exeption/slug/.+) part seems not to work. How do I have to do it to make it work?

I need this e.g. to handle custom post type categories as they are not supported by this plugin (Q&A, bbPress, portfolio, ...).

Thanks and cheers, Alex