There is some question as to the legal status of re-using tables - in the absence of any clear legal guidance I think that we should err on the side of safety and not allow tables from commercial BIOSen.
It wont work because lot of I/O resources is static in the ACPI. Creating some minimalistic ACPI tables should not be too difficult.
http://www.coreboot.org/ACPI_in_coreboot
Rudolf