The Anzob Pass is still closed but it is possible to drive from Dushanbe to the North via a tunnel still under construction. Embassy staff are prohibited from using this tunnel when driving on official business. This road is particularly dangerous in winter due to icy conditions and frequent avalanches and drivers can be trapped for a long time if caught in an avalanche because of the uninhabited mountain terrain.
So if the Anzob Pass is closed, you can take the tunnel. Although the Anzob Tunnel is “still under construction,” apparently it’s possible, by times, to drive through it, as demonstrated by this this round-the-world cyclist who shot video of his trip through the tunnel.
If the Anzob Pass happens to be open, it will take some time; according to the United Nations Development Program you can:
Drive from Tashkent via Khujand and over the passes to Dushanbe — spectacular, best done by driving first to Khujand and spending the night there in the UNDP guest-house, then leaving the following morning. The drive from Khujand takes 7 hours, but one should not hurry, so allow a full day. However, the southern of the two passes, the Anzob pass. Normally the pass opens for regular traffic in the last week of May or thereabouts.
I have come to know all this because I suddenly became entranced with the idea of attending BarCamp in Dushanbe on November 26, a dream that, alas, I’m fairly confident I won’t realize.