There is nothing that you can do that will make you feel completely ready for the exam on test day.
The most you can do is take practice tests in real-like conditions as possible. There is simply no way to mimic the adrenaline in your system during the real test. If you can constantly remind yourself that the practice tests are VERY VERY strong indicators of real score predictors, this can help you to be "more nervous" during the practice tests.
I read something from LostInStudy's thread and it helped me during my test. Basically, I had a "ritual" I did every time I started to freak out/get stuck any time throughout the test. By the time I used this technique enough, I was good at being in "crisis management" mode and not freaking out. Take a deep breath, and try to not reread the question/answer over and over, because this will only cause for more nervousness. Try to close your eyes and take a deep breath and actively remind yourself you put X number of hours studying for this test, and you are as prepared as you will ever be, and you are capable of owning the test. Use your adequate preparation as a way to calm yourself for the test.