Not sure about "schedule" S shares but I have some knowledge of "Regulation" S shares. The Reg S shares changed some time back to the 1 year hold period which sounds similiar to the situation you are in. The only way you can sell them is via a private transaction with a buyer (for buyer read long term investor) who wishes to hold them for at least the remainder of the holding period. That buyer will probably be more interested in the fundamentals of the company i.e. will the company still be around in a years time?, and the potential of the company rather than how many shares it trades, although that will still be of interest to any buyer. There are, or at least there were when I was last involved in these things, some funds that would buy these shares and hold them until the holding period had expired, it might be worth trying to find if any of these funds still exist. Bear in mind that selling to these funds or to private buyers will incur a heavy penalty and you may only get 20% of what you paid for them assuming you didn't buy them at a falsely inflated price.
There was another option which I think was outlawed (again you will have to do some research into it) and that was you would take out a loan against the shares (using them as security) and default on the loan, the loan company would then call the loan and apply to have the restriction lifted on the shares so as to be able to extinguish the loan. Again expensive as the loan was rarely more than 50% of stock value.
It may be worthwhile looking into the regulations concerning the sale of these securities, check with the FSA in the UK and also check the regulatory body of the agent selling the shares - I guess though that the agent was an offshore entity and not US based? There may be some kind of recourse if the agent has acted improperly in the sale process.
Were you aware of the holding period before you agreed to buy the shares?
