Hi Hilton,
as Runjhun said, it is not possible to do it in standard. You need at least add location as customer field for other object types (phase and task), so that you can maintain them directly in PPM.
Secondly you need to pass the values from PPM to ERP system, I think, some BAdI you can use for this purpose.
At last, in the ERP side, you need to map the location to plants using some logic, and make sure, that the information is used.
Not very easy, but should be possible.
Kind regards,
Zhenbo