Superuser.apk, needed by all builds to protect your system against unwanted root calls. Also, when superuser.apk is build the root SU binary is placed as well.

cd ~/android/system/packages/apps
git clone -b eclair http://github.com/cyanogen/android_packages_apps_Superuser.git Superuser

after the source has been downloaded a file needs to be modified so that the AOSP SU binary will not be made.

gedit ~/android/system/system/extras/su/Android.mk

in the text box that opens remove the current text and paste in the following

ifeq ($(BUILD_ORIGINAL_SU),true)

LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)

LOCAL_SRC_FILES:= su.c

LOCAL_MODULE:= su

LOCAL_FORCE_STATIC_EXECUTABLE := true

LOCAL_STATIC_LIBRARIES := libc

LOCAL_MODULE_PATH := $(TARGET_OUT_OPTIONAL_EXECUTABLES)
LOCAL_MODULE_TAGS := debug

include $(BUILD_EXECUTABLE)

endif

all following builds will now have both Superuser.apk and Root