It's not beyond the scope of most electronic hobbyists to add an RF transmitter to their CD player or whatever that could broadcast on the ILS frequency band. If the device contains an FM receiver you've already got an oscillator that operates at the correct frequency (just about). This article implies that one of these devices would make an aircraft fall out of the sky which is sensationalist claptrap.
However, I would ban CD players and Walkmans anyway as the ssss ssss ssss noise annoys the hell out of me....