How to enable PCIE2 on BPI-R2

is there any documentation somewhere on how to run the PCIE2 slot instead of the USB3? I have tried this here:

I get the dmesg message

mtk-pcie 1a140000.pcie: Port2 link down

on r2 the pcie slot and usb3-ports working together…or which pci-slot do you mean?

I mean the one that is led out as a pin header. According to this description it can be used as PCIE via “PIN DEFINE”

Edit: I would like to use the connector similar to this: