How Do You Talk To Steven In The Museum In Soul Silver?

You need the key item called the Enigma Stone. But it can only be accessed with an Action Replay or special event. If you do have a Enigma Stone you should:
- Talk to Steven.
- The Enigma Stone will turn out to be a Soul Dew, a special item for Latias and Latios.
- Get ready to battle because as soon as you leave the museum Latias (Soul Silver) or Latios (Heart Gold) will appear. Battle and capture it.

Good Luck!