After setting up my new router (described here), I've decided that only using TOR is not enough. Thus I've added 'Freifunk' functionality to the router as well.
Thankfully the Freifunk firmware is completely based on OpenWRT. After all that effort getting my router to work properly I didn't want to just re-flash everything and losing all of the settings I had just added.
Instead I got myself a copy of the current firmware (http://fw.freifunk-rhein-neckar.de/) and unzipped it. Then I followed the instructions on the wiki to manually configure my router to join the Freifunk network.
Sadly the instructions were not completely applicable - as is stated on the site itself they were slightly out of date. Also I wanted to keep my firewall settings as complete as I could - so I had to change some of the /etc/config/firewall rules to keep my settings.
But in the end I was able to connect to the Freifunk net using client hardware! So I assume everything is working as it should. Yay for free (as in freedom) internet!