It’s installed. Yay! 😀
I ended up skipping the ipkg version. It wouldn’t install the correct package.
After doing a clean firmware install and using the Synologi Wiki + the updated files from the forums I managed to install without too much fuss. Some library paths were not entirely right, but I managed to solve it.
I’ve now got a perfectly tuned iTunes server for my Soundbridge! Time for heavy metal 😈