Installing FreeBSD 11 on PowerMac G5 (beside Debian)

I have a G5 Power Mac with Linux and i would like to install FreeBSD on it. However, whenever i try to install it, it completely destroys the partition tables on ALL disks and rendering Linux to unbootable. (FreeBSD also cannot boot.) I've read in the manual, that on PPC sysinstall cannot properly partition and i should use gpart instead, but i did not asked it to partition anything at all! I just asked it to install on a pre-made partition.

My question is, how can i install FreeBSD on my G5, without destroying my disks. I have the following partition tables:

A 120 GB SSD with:
4 MB Apple boot partition
16 GB ext3 for Linux
16 GB UFS for FreeBSD
88 GB unpartitioned

A 80 GB HDD with
16 GB swap for both systems
64 GB ext3 for data

So, how can i make FreeBSD understand to don't mess with the partition table and just install to disk0/3 and use disk1/1 for swap area?

Any help is appreciated.
Hello .
I have received 7 G5s and 3 G4s Apple Power Macs in an old Job lot of Computers from an Office clear out .
I would like to repurpose these computers - primarily as Dual Boot Mac OS X (for teaching Photoshop)
with a more modern OS like a BSD or Linux OS .
I have the same problem while dabbling .
Your solution is to NOT go into the on Disk Installation process but to
copy the BSD .ISO file to the Second partition on a Pre-partitioned Hard disk with Debian (for example) already installed on the first partition .
Extract the ISO to the 2nd partition - this will be a copy of the Installation Image .
Next step is my question is -
Do you run the installation by going into the Open Firmware of the G5 and running some commands to link and start the installation script
Find a way to Bootstrap the installation using a CD with an executable script from there ?
Another problem is 32bit BSD with a 32bit Open Firm ware or 32bit BSD with a 64bit Open Firmware - is this relevant ?
( I know Open Firmware is similar & a precursor to Intel's EFI ) .

Even if I don't receive a reply - I will eventually find out how to do this by researching on the web
BUT anyone else reading this POST can leave a message to see how I am getting on !
Put a second disk and install FreeBSD on it?

Hello .
I trying this as we speak (in REALTIME !!!) and although it looks like it works at the beginning of the install , it hiccups and stops half way through Ncurses screen at the partition menu .
The nature of G5's means that you have to close the case completely to do anything correctly where air flow and heat dissipation are concerned .
I will swap out all the cabling then go to a 2nd and 3rd HD if needed as a practiced problem solving procedure .
Still studying the Open Firmware commands and formatting preferences for a BSD install - UFS is the standard file system so will stick to that .
ZFS is too advanced for me at the moment .
Probably a Partitioning problem , I think it might be APM as opposed to GPT as it is the original HD .
A second hard disk is probably the best way to go , lots of room in a G5 and I have 30 odd hds (40 to 320gb) to laying around choose from .