Do I need special permission to enter the Tajik Autonomous County(Tashkurgan)? And how can I get it

Hello! We are planning a trip from Kashgar to Sost (Pakistan) through the Khunjerab Pass in early May. At "Wikitravel" I found information that: "As of October 2011 foreigners could not enter the Tajik Autonomous County without being part of a tour group or having a special permit".
Can you confirm or deny this information?
If we really need a special permit, where we could get it and how much will it cost?
Thank you.