There should be a timeline in the material editor too. I use B5.5 but it should be similar (I've just tested this to make sure I not talking cr*p too) After setting the animation up in the main window, select the surface of the object whose material is to change. Go into the material editor. Press the key button at zero time (or whenever you've entered the lab) to add a keyframe. Now move the slider to the desired time and make your changes. A keyframe should automatically appear, press the key button to make sure. When you're done, exit material lab using the green 'tick' button. IM me your e-mail and I will send you the test file I've done if you like.