He write, what he install d170 stok rom from kdz and over it install CM with changed build.prop and all works!
http://4pda.ru/forum/index.php?showtopic=632951&view=findpost&p=39670189
Did that now. I extracted the partition images from the D170 kdz, wrote them to the phone's respective partitions (all except aboot and recovery, so that i won't lose the unlocked boot loader and CWMR.
Then booted it and verified that it consideres itself to be a D170 now.
Wrote boot.img from the cm-11-20150325-UNOFFICIAL-w3ds.zip to the boot partition (i guess that happens implicitly while installing CM, but whatever)
Then installed the cm-11-20150325-UNOFFICIAL-w3ds.zip using 'install zip' in CWMR. (Edit: with the modified build.prop; gpio-keys.kl are identical between D160 and D170))
Booted it, and yes, it's CM now.
And no, neither wifi nor camera work. So this was rather futile. I wonder what your friend did differently....
PS: If it's useful for someone else, the .kdz's can be extracted with
https://github.com/thecubed/kdzutils, but it will complain about the header magic being wrong. It turns out that the format otherwise is the same, so changing this line
https://github.com/thecubed/kdzutils/blob/master/KDZFileTools.py#L24 to the header bytes (which the script tells) causes it to work for the D160 and D170 kdz files. The license of that tool prevents me from uploading a modified version; quite useless.
After extracting the .dz file that was extracted from .kdz, it turns out some partition images come in multiple files.
I wrote this (shell) script to merge them together, feel free to share/modify.
http://penenen.de/glue.sh should work in every POSIX shell; run with -h to get a usage statement