I feel exactly the same way, and with age I'm getting more and more worried about this, but still I prefer DIY.
You need to remove the 3 'wooden' panels in your car - first the bezel around gear, second the ashtray and cover and third the wooden cover of the head unit. The bottom of the navi will then be exposed and you can connect the aux. There are many online videos on it. But take not that my CL9 is non-navi so I'm not 100% sure that navi panel has a connector for aux beneath it.