If they were going to be used anywhere else, it would have to be with one of the Gas Giants, because no other planet has enough magnetic field in the solar system to use them. Furthermore, it would be an orbiter of some kind, because it wouldn't make sense to use them for only the short period of time when flying by the planet of interest. Thus, the candidates are JUNO, Cassini, and Galileo.
- Cassini - Uses Reaction Wheels and thrusters
- Galileo - Primarily managed via spinning the spacecraft and thrusters.
- Juno - Just uses thrusters, along with being spin stabilized.
Bottom line is, none have done it. They could probably be used, but as magnetorquers are somewhat limited in their ability to point specifically at something at a given time, and there isn't as much movement of spacecraft as they would be on Earth, and as the orbits are quite slow by Earth standards, I don't think it would gain much, thus, it hasn't been tried.