I wanted to make OmniROM to look like a stock Sony XPERIA firmware, the one has nice signal bars and navigation bar symbols in particular, so I extracted necessary files from original SONY firmware and prepared them to merge with OmniROM nightly that I download and flash from time to time. Maybe someone will find these useful so I'm sharing them here along with instructions:
I advise to use 7-Zip to work with the nightly you download. You may do the same with native Windows explorer, but I wouldn't trust how it will re-pack apk archive.
1. Merging framework-res
a. Go to \system\framework, find framework-res.apk, open it inside 7-Zip as archive
b. Go to \res\drawable-xhdpi and paste there appropriate files from the attached archive
c. Go to \res\drawable-xxhdpi and paste there appropriate files from the attached archive
d. Close the archive saving (updating) all the changes in it
2. Merging SystemUI
a. Go to \system\priv-app, find SystemUI.apk, open it inside 7-Zip as archive
b. Go to \res\drawable-xxhdpi and paste there appropriate files from the attached archive
c. Close the archive saving (updating) all the changes in it
3. Your styled ROM is ready to be flashed.
THESE FILES ARE ONLY FOR 1920x1080 PORTRAIT ORIENTATION DEVICES (NOT TABLETS!)
XPERIA - framework-res.zip - for styling framework-res.apk
XPERIA - SystemUI.zip - for styling SystemUI apk
XPERIA + Android L Navbar - SystemUI.zip - for styling SystemUI.apk, navigation bar will look like Android L (triangle, circle and square), images are pulled from NEXUS 5 Android L Developer Preview image