workke,

Even if you don't have a CD changer, your MINI should be pre-wired for a CD changer. Look in the boot pocket in the back, there should be a bundled up set of cables. There are two connectors for the CD changer - the one that is smaller, with only 3 or 4 wires in a straight line, is the I-BUS connector.

That is the easiest way to tap in to the system.