This is how you do it:
Sneak one character onto the top right switch (the one without the Sentinel)
Sneak another onto to the top left switch, with the Sentinel you have now deactivated.
Then, sneak another behind the rocks near the bottom left switch. Wait for the Sentinel to turn away first, then sneak onto that switch.
Lastly do the same for the bottom right switch.
Once you get to a certain point in the game you can just walk up to the statues and smash them. Makes it a lot easier.
