DataSource Controls :: Calling Stored Procedure With Hierarchyid Parameter?

How do you call a stored procedure using C# .NET 3.5 that contains a parameter that is of type hierarchyid in SQL Server 2008?

A basic outline of my current code is as follows:

SqlConnection conn =
new
SqlConnection(DatabaseConnectionString);
SqlCommand StoredProcedureCommand =
new
SqlCommand("AddUser", conn);
StoredProcedureCommand.CommandType =CommandType.StoredProcedure;
SqlParameter ParamUsername = StoredProcedureCommand.Parameters.Add("@Username",
SqlDbType.NVarChar);
SqlParameter ParamPassword = StoredProcedureCommand.Parameters.Add("@Password",
SqlDbType.NVarChar);
SqlParameter ParamMasterNode = StoredProcedureCommand.Parameters.Add("@MasterNode",
SqlDbType.Text);
// HierarchyID type
ParamDynamboUsername.Value = Username;
ParamPassword.Value = Password;
ParamMasterNode.Value = "/";
conn.Open();
StoredProcedureCommand.ExecuteNonQuery();
conn.Close();