You could use MTM with your Testcomplete scripts. You need to create a visual studio solutions which would store your testcomplete scripts. Then, you can associate your testcase work item to the automated test from the visual studio solution to the testcomplete script.
If that is what I think you are trying to accomplish. Microsoft Test manager is just a way to categorize test plans, test suites and test cases. It is not a replacement for TestComplete8 script unless you want to convert it to Visual Studio.