an MMU is needed, particularly one that is compatible with an available simulator or preexisting implementation. power-gem5 has a well documented implementation.
https://github.com/power-gem5/gem5/commit/373f7af347628151d23e6a5f81ae280f686df1f2 example https://github.com/power-gem5/gem5/blob/gem5-experimental/src/arch/power/radix_walk_example.txt
interesting reading: https://yarchive.net/comp/powerpc_page_tables.html