Today I had the same problem. I resolved it in the following manner:
First install;
sudo apt-get install xul-ext-torproxy tor
Then, you need to download the necessary debs from here (lang and arch):
http://devel.trisquel.info/icecat/belenos/pool/main/i/icecat/
and install it (one by one) using dpkg. First icecat, example:
sudo dpkg -i icecat_31.0+gnu3_amd64.deb
Likewise for the language pack (If this is the case). After (If you have
added the ppa):
sudo apt-get update && sudo apt-get dist-upgrade
