It depends if you're talking 2D or 3D. If its 2D, then thats all in programming of your map routines.
In 3D, you're talking about collision events. There are lots of ways to do this, but generally I use a pivot point in space to represent the "hotspot", then use ENTITYCOLLIDED and COLLISIONENTITY to see if that point was hit by the player entity (1) and to carry out actions when that collision occurs (2). Unfortunatey I'm at work so can't post any examples, but have a look at those commands. :)
BlackD
In 3D, you're talking about collision events. There are lots of ways to do this, but generally I use a pivot point in space to represent the "hotspot", then use ENTITYCOLLIDED and COLLISIONENTITY to see if that point was hit by the player entity (1) and to carry out actions when that collision occurs (2). Unfortunatey I'm at work so can't post any examples, but have a look at those commands. :)
BlackD