The Wiki::Formatter series is a framework to convert various wiki markup formats into HTML. Maybe you can abuse/subvert Wiki::Formatter::Kwiki to do what you want, or recreate Trac markup from the HTML generated by it. One problem is that the Kwiki formatter seems quite unsupported and left behind with CGI::Wiki, while development has moved on to Wiki::Toolkit.

Another usable fork of the Kwiki formatter might be Text::KwikiFormatish, but with that as well, you will need to create the conversion back into Trac format yourself.