I would handle it this way:
The boots have a manipulating effect on the one wearing them that makes them want to dance.
Whenever he hears music he can't help himself and starts dancing. This dancing starts out pretty harmless, but he just can't stop. If nobody takes care of him he will start to get exhausted after a short time and later will take increasing damage until he dies from a heartattack or falls uncounsious (<- damn difficult word). Maybe the nonstop dancing will also cause breaking bones and traumatize the victim.
Somehow it also causes a pressure which will causes the wearing person from time to time to do a harmless spontanous dance. If he tries to surpress it he has to pass a check, what will make the next time more dangorous.
I didn't mention exact times because I am kinda new to DS, but this would be how I would basicly handle it.