When the Siren is waiting for you to touch her just
 click on the lower left holo-ball. This will put you
 cheat mode. Now when you perform an action on the Siren
 such as rub breast. The indicator next to the siren model
 will turn green if you are performing the correct action.
 (usually it is always red)

The Spoiler Centre
Walkthroughs on Adventure Gamers
| Gamers Manual - Gaming guidebook