According to my game guide the only way to get the pyromaniac trait (also known as the Hidden Trait) is to marry a fire fighter and have a kid. What I would to is:
A) cook on the cheepest crappiest stove and just wait for a fire.
B) cook on a stove and walk away and wait for the fire to start. (This way is the fastest and easiest)
C) If you have a fireplace put a rug or piece of furniture in front of it, as close as you can get it and boom a fire.