How to connect SPI2 in PCIe x16 connector (J6) of AGX Xavier Devkit?

In SPE firmware (AGX Xavier), SPI2 is used as a example. But I can’t find a way to connect it, because it is hidden in PCIe x16 connector (J6). I want to the PCIE extension cable to connect it. However, these pins(A5~A8) are not used in the standard PCIE extension cable. Is there any way to connect it? If not, does it mean only SPI1 in 40-pin header can be used? Thank you in advance for your help.
SPI2 Pin Description:
PCIE spi2
PCIE extension cable:
PCIE延长线

@Trumany
Please help to give advice for this topic.

Thanks

You can solder some lines out from the pins if possible.

I don’t think it is a good way. Can you give more convenient and reliable method?