Hello,
When you launch a new execution you can get a reference to the execution. You will need to create a local variable in TestStand that is of type ActiveX Reference, that will store this new execution reference. You can then pass this reference to your DLL as an IDispatch. Once you have this reference, you can then call the method Execution.GetThread. Now that you have the thread reference, you may call the method Thread.GetSequenceContext.
Hope this helps!