Hopefully, in time, the ROM devs will add this in by default or as an option. Until then it'll require these manual mods...
Don't try the following if you're unsure what you're doing as you could potentially break the ROM if not done correctly. I recommend backing up first in Clockwork Recovery in case things go wrong.
I accept no responsibility for any issues encountered making these changes!
baksmali/smali from here
Step 1 - Update android.policy.jar
1. Do the following to get the android.policy.jar from your phone and disassemble it
adb pull /system/framework/android.policy.jar . baksmali -x android.policy.jar -o classout
4. At the bottom of the method, there's a switch statement. Remove the following 2 lines from it:
0x18 -> :sswitch_5 0x19 -> :sswitch_5
6. Run the following commmand to re-assemble classes.dex
smali classout -o classes.dex
8. Push the updated android.policy.jar back to the phone
adb push android.policy.jar /sdcard/ adb shell su sysrw cp /sdcard/android.policy.jar /system/framework/ chmod 644 /system/framework/android.policy.jar
Step 2 - Update Generic.kl
1. Pull the file from your phone
adb pull /system/usr/keylayout/Generic.kl
key 114 VOLUME_DOWN key 115 VOLUME_UP
key 114 VOLUME_DOWN WAKE_DROPPED key 115 VOLUME_UP WAKE_DROPPED
adb push Generic.kl /sdcard/ adb shell su sysrw cp /sdcard/Generic.kl /system/usr/keylayout/ chmod 644 /system/usr/keylayout/Generic.kl
Reboot the phone.
Note: The first time it boots after changing android.policy.jar, there'll be an 'Android is upgrading' dialog. This is normal and it won't happen on subsequent reboots.