You could make your own word dictionary, pick 12 random words (and append a few random characters to the end of the string) and come up with your own hash.
Now that you have the hash and the word dictionary, you "forget" that you know the real string, and you set your program to try to find it.
At least that would make sure there weren't any major bugs in it (logic bugs not included) before you tried to solve the real problem. Since you only have 24 hours to crack it, every extra second will count ;)
Of course you'd have to write the application before the 20th. My point is that for people with day jobs, Mondays are almost always the busiest day of the week so I'm sure that will preclude a number of people from participating.
Now that you have the hash and the word dictionary, you "forget" that you know the real string, and you set your program to try to find it.
At least that would make sure there weren't any major bugs in it (logic bugs not included) before you tried to solve the real problem. Since you only have 24 hours to crack it, every extra second will count ;)