This short guide assumes you're on Ubuntu 11.04 or above
First, we need to create directories for the build (system can be whatever you want to name your working directory):
$ mkdir -p ~/bin
$ mkdir -p ~/android/system
Now we'll need repo. Let's download it and make it executable:
$ curl https://dl-ssl.google.com/dl/googlesource/git-repo/repo > ~/bin/repo
$ chmod a+x ~/bin/repo
Log out and back in so the changes take effect.
Now initialized the repository and pull the source (with my repos attached):
$ cd ~/android/system/
$ repo init -u git://github.com/CyanogenMod/android.git -b ics
$ repo sync
Depending on your connection, this might take awhile.
Getting my Huawei Mercury repo
$ cd ~/android/system/device/
$ mkdir lge
$ cd lge
$ git clone https://github.com/playfulgod/android_device_huawei_c8860.git c8860
NEED FILES FROM ICS LEAK!!!
We will need to reuse some proprietary files from the stock ROM:
$ cd
$ cd ~/android/system/device/huawei/c8860
$ ./extract-files.sh
Once thats done you can start compiling.
Follow the aosp instructions on setting up the build environment. - http://source.android.com/source/download.html
When the environment is setup, we need to grab a copy of Koush's ROM Manager and the Term.apk. This is necessary to build CM9.
$ cd ~/android/system/vendor/cm
$ ./get-prebuilts
Now, we build (system being your work directory):
$ cd ~/android/system
To build for the Huawei Mercury:
$ . build/envsetup.sh && brunch c8860
If the build was successful, you can now take the update zip found in out/target/product/c8860/ and flash using a custom recovery. Make sure to grab the latest Gapps to complete the experience.
When you want to rebuild with new changes to the BoardConfig.mk or after syncing to the latest CM src make sure to do the following before you recompile.
$ make clobber
Based off fredv's u8860 repo