David Malczyk on rooted phone:
1.unzip update.app by HuaweiUpdateExtractor_0.9.8.0
2. unzip cust.img by 7zip or other like simple .zip file.
3. Copy cust folder from this file to sdcard.
4. Plug phone to ADB and write commands:
adb shell
su
mount -o rw,remount -t ext4 /dev/block/platform/msm_sdcc.1/by-name/cust /cust
5. By Root Explorer (Root Browser or something like that), copy "/cust/" folder from sdcard to root directory "/" and overwrite.