Sure. You can make the civillian a passive critter that calls for help. Make the guards passive critters as well. I'm not sure if it will work smoothly in Blizz-ABS 1.89, though, but it will in 1.9 when I release it.
About the sneaking thing:
In the 4th tab of the event command "Conditional Branch" you can see a text input window that says "Script" right before it. Activate it and you can use the attribute "$game_player.sneaking?" (without the double quotes) to check whether the player is sneaking or not. Simply add it all to a parallel process where this condition is checked constantly and add a damage command. Also add a wait command so the damage is not inflicted each frame, which would be 20 times a second.