Load testing WCF operations.

Question

we have requirement that we need to test the wcf operations in load environment to analyse performance of server.

I have developed test cases for wcf operations. Each Test case executes Connect(which connects to application, after that only we can able to execute other operations) so each test case has a dependancy on connect TC. I need to simulate a load pattern like , 20 users connect using testuser1 configuration(configured in xml) and do some wcf operations & 30 users connect using testuser2 and  do some wcf operations. i dont want to develop seperate TC for testuser1 & testuser2 . The only one TC connect should be able to connect to Application using different credentials , is it possible . I have used Data driven approach & it didnt worked out for me. please suggest something.