(this is assuming you use 2k3, dunno how XP opertates cuz I'm too poor and lazy to buy it)
you would use a switch and set it ON when the player uses the action key on the tile in front of the object. Now there's two ways of doing a fireplace or other animation:
1) Have one event with two pages, and a sprite sheet with an animated fireplace. On the first page set On the second page, see the conditionals on the left side of the page, above the animation settings? Check one of the switches and set it to the switch you're using. Now set the graphic tothe fireplce animation.
2) set it up like 1, but instead of switching the graphic, turn the event into a Parallel Event. Now, make a battle animation for the fireplace, and in the fireplace event have it use the Show Battle Animation command and select the fireplace battle animation. You don't have to use it in combat, and this approach can also allow you to make little exclamation points appear over peoples' heads and stuff like that in cutscenes.