You might be able to get it through the fresh air vent. The place where air is drawn in by the AC/Heater fan. There is a filter screen which you would have to push the wire through but a small hole in there shouldn't be a problem. At least it never has been for me. You just have to put the wire through in such a way that it doesn't block the systems ability to select between fresh and recycled air.

Just a suggestion. Attempt at your own risk.