I had the same problem as you building the attached solution and that was the only decend way i found. Script itself is not complicated, please find mine below:

public void Main()

{

bool IsValid = true;

string Provider = "SQLNCLI10.1";

string ServerName = Dts.Variables["User::ServerName"].Value.ToString();

string Catalog = Dts.Variables["User::Catalog"].Value.ToString();

string UserId = Dts.Variables["User::UserId"].Value.ToString();

string Password = Dts.Variables["User::Password"].Value.ToString();

OleDbConnectionStringBuilder builder = new OleDbConnectionStringBuilder();

builder["Provider"] = Provider;

builder["Data Source"] = ServerName;

builder["Initial Catalog"] = Catalog;

builder["User ID"] = UserId;

builder["Password"] = Password;

OleDbConnection connection = new OleDbConnection(builder.ConnectionString);

try

{

connection.Open();

}

catch

{

IsValid = false;

}

if (IsValid == true)

{

Dts.Variables["User::ConnString"].Value = builder.ConnectionString;

Dts.TaskResult = (int)ScriptResults.Success;

}

if (IsValid == false)

{

Dts.Events.FireError(0, "Connection Error", "Error initialising connection to server: " + ServerName, String.Empty, 0);

Dts.TaskResult = (int)ScriptResults.Failure;

}

}