I have no idea about how it works. That was a suggestion of our tour agent. I couldn't even imagine it is possible. It seemed we were alone at the palace: 4 of us, our guide and the palace security. We've heard the crystal chandeliers'jingle when walking around the halls....That was an unforgettable visit
I believe Anastasia Travel (http://www.anastasiaworld.com
)would be glad to answer all your questions.
Enjoy your trip