I like to provide the best solution I have found so far. Maybe someone else is also looking for this kind of tool in order to export from DokuWiki -> Indesign. Here is what I found out:
1) In order to export a complete DowkiWiki, use the "site export" plugin
2) To output Indesign content, i refer to a plugin created by user 'krank' (all credits to him - great work !!!). It outputs the site content as "Indesign tagged text" format. This is a bit like "poor man's xml". Find the renderer attached to this posting. Here you find how to install it:
https://www.dokuwiki.org/devel:renderer_plugins
3) Run the site export and chose the Indesign plugin as renderer.
4) Open the export in Indesign and import it there into a text field (using the "file > place" command). Indesign will then auto-layout the text. The cool thing: Paragraphs are editable using the Indesign settings. You can edit headline formats and all text will modify automatically. This way you can then built up your DokuWiki content in a nice print layout.
Downside so far: Images are not exported. They need to be integrated in Indesign later manually.