Your settings are not present/documented in the generated text files, are you sure? Someone could brick the motherboard
Honestly,
I do not remember how I found it, but I found it in text files, the part that I could not find is PCI_COMMON. I could find the other part in SaSetup.
Anyhow, this whole thing is at your own risk, everyone should know it.
It works fine still for me, and I have posted this just for my reference so I could find it in case of BIOS upgrade, but since the MB is old, its unlikely to happen. As far as I know Lenovo being pain in the backside and blocking these features because you have not paid enough money to them just made me sad, so I though well hell, this MB has everything I need, just not in the UI 
PCI_COMMON has the hex code and if you search for it I believe you will find something related to ReBar.