Basic steps to build:

1 - Get local copy of CM7 respository
2 - Get copy of the device tree into device/htc/heroc
3 - Copy modified files from 'device/htc/heroc/buildmods' to proper directories:
        a) definitions.mk.heroc to 'build/core/definitions.mk' (Temporary fix for boot.img size issue)
        b) vendorsetup.sh into 'vendor/cyanogen' (Add lunch combo)
        c) prelink-linux-arm-heroc.map into 'vendor/cyanogen' (Map library locations)
        d) AndroidProducts.mk.heroc to 'vendor/cyanogen/products/AndroidProducts.mk' (Add cyanogen_heroc product)
        e) cyanogen_heroc.mk.heroc to 'vendor/cyanogen/products/cyanogen_heroc.mk' (Add cyanogen_heroc makefile)
4 - Run get-rommanager in vendor/cyanogen directory
5 - 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')
6 - Setup build environment by sourcing envsetup file '. build/envsetup.sh'
7 - Run Lunch to select the build target 'lunch cyanogen_heroc-eng'
8 - Build the system with make, mka, etc.