The biggest pain in the ass is a rear mounted/secured HU. I installed one on a coworkers honda, and it required the glove box, drivers lower dash, and center console be removed. I don't recall seeing an front removal screws on the e46, although I havent though to look whenever Im in it.
<span style='color:gray'><span style='font-family:Courier'>1995 e36 3 Series RIP
1999 e46 3 Series BURN IN HELL
2000 MR-S Roadster= Current</span></span>