Yes...the maintainers would be very interested, but unfortunately we are working flat out on new developments at the moment so time is a scares resource and adopting ports is a time consuming exercise (testing, updating, quality control, documenting etc.).
Depending on your budget, you could contact the folks at High Integrity Systems
to see if they could assist as their safety work takes them more in the the PPC world.
How different is the device to the existing PPC4xx ports? Maybe you could start with the source code for one of those? There is a little bit of help in the porting guide
, but there is not really any generic text that can be written about the guts of any particular port as how the port is written is very dependent on the functionality of and facilities provided by individual CPUs.