Tony Ross have a great tutorial split in 3 videos, which helps you to setup a nice optical illusion on Flash CS3.

• Video 1 – In this video tutorial, Tony Ross demonstrates the first of a 3 part series, creating optical illusions in Flash. Create a spinning illusion of circles with cycling gradients using Motion Tweens and Rotation Options. Tools used include the Oval Tool, Free Transform tool, Gradients, and an introduction to the History panel.
• Video 2 – In this video tutorial, Tony Ross demonstrates part 2 of a 3 part series, creating optical illusions in Flash. Create a tunnel illusion using Motion Tweens and Masking. Tools used include the Oval Tool, Free Transform tool, Gradients, and the History panel.
• Video 3 – In this video tutorial, Tony Ross demonstrates part 3 of a 3 part series, creating optical illusions in Flash. Create a more complex spinning illusion of two sets of concentric circles using Motion Tweens, Rotation Options, and Blend Modes. Tools used include the Oval Tool, Free Transform tool, Gradients, and the History panel.