Basic steps to build:

1 - Get local copy of CM7 respository
2 - Get copy of the device tree into device/htc/heroc
3 - Run get-rommanager in vendor/cyanogen directory
4 - Get proprietary files into 'vendor/htc/heroc/proprietary'
        a) Put ROM (update.zip) in repo root and run 'unzip-files.sh' from the 'device/htc/heroc' directory
        b) Use 'adb' to pull files from usb connected device by running 'extract-files.sh'
        c) Copy files from expanded system directory on your local machine by running 'copy-files.sh'
        d) Copy files from 'device/htc/heroc/proprietary' directory (also needs 'setup-makefiles.sh')
5 - Setup build environment by sourcing envsetup file '. build/envsetup.sh'
6 - Run Lunch to select the build target 'lunch cyanogen_heroc-eng'
7 - Build the system with make, mka, etc.