It's less a matter of a matrix thing than it is something you can do with any player. They get the commlink with the red-embossed X (not just tape, but custom-made), and when they start using it, whomever is behind it starts tracking what they do. And then it starts asking for certain minor things, promising that the carrier - be he decker, rigger, samurai, or mage - 'karmic reward'. And often, later on, you can put in a request and voila', it will help you out.
But screw them over even once, and your life will become a living hell, at least for a little while.