FYI, the method of copying the image to your N9 is slightly different, the easiest way is this way:

1. turn off your device
2. attach the cable to your pc
3. connect your pc to your device via cable
4. wait for all partitions to be mounted
5. now in your file browser (eg. dolphin in mint) go and find partition called AltOS, just double click on it, it will mount and will be ready for our procedures

now follow this way:
first extract the xz image by any decompressors which support xz format archives, you will end up with a 1.3GB file size called
sailfish-hv-1.1.0.39-20141110.img
now you have to simply mount the image to your pc first
by using this command in linux:
mount sailfish-hv-1.1.0.39-20141110.img /mnt
now you have to copy the content to your device:
cp -a /mnt/* /media/AltOS/
#NOTE the AltOS must be mounted and ready
#depending on your LinuxOS, the AltOS mount point would be different mine was /media/max/AltOS
DONE
I hope I explained it in easy and understandable way