Thank you @
InertiaSelling! The HoRNDIS tip saved the day!
@bbst: I'm using the Clover 3 folder. I've only tested the DP port and LAN port via the docking station and they both work perfectly. I did have to install this driver for ethernet to start working (although MacOS did see the ethernet port, it didn't work):
http://download.sharkoon.com/0012-RTUNICv1.0.17.zip
The internal speakers in my laptop work fine, right out of the box (thanks to the provided kext files, I suppose).
I had to place the VoodooPS2 kext in /Library/Extensions for my keyboard to function after a cold boot (without reboot).
Once I've received my DW1560 everything that's important will work. For now an USB bluetooth stick and HoRNDIS + my android phone cover what's missing. Very happy with this thread and my Precision 5520!
edit: @
blazinsmokey I think the thread title should say "[Guide] Dell XPS 9560/Precision 5520....". The only significant difference (in regards to the subject) between the two devices is the wifi/bluetooth card. The GPU can be ignored, since in both cases they don't work anyway.