AJ:
You have to place the entity on the map editor then use what you said above to set the parameters.
Set Entity.
Set Maximum To Spawn to 1 (unless you plan to have him spawn again and again after death).
Set Spawn at Start to NO.
Set Spawn After Delay to YES.
Set Delay to 10000.
Apply Changes.
Make sure you name the entity too. You will need this name for the trigger zone.
Set trigger zone.
For MAIN, use playeractivatedifused.fpi
Then for If Used, type in the name of the entity to spawn.
Try this and see if it helps.
GAME ON!!!!
--King Cobra