You can sign up for an account on https://www.primarymarkets.com which is the platform the shares are being moved to. I don't know yet how you link your shares to that, but that will become apparent in the future.
Be aware that to trade on Primary Markets you need to be a verified sophisticated investor. I read a post here somewhere that someone mentioned the possibility of being able to have a restricted account for selling only SPT shares which would not require sophisticated investor verification.
