Here are some hard to find files you would like to edit before compiling main image:

To edit network settings:
  <...>/carambola/build_dir/target-mipsel_r2_uClibc-0.9.32/root-ramips/etc/config/network

To edit Wireless parameters:
  <...>/carambola/build_dir/target-mipsel_r2_uClibc-0.9.32/root-ramips/etc/config/wireless

To change banner message:
  <...>/carambola/build_dir/target-mipsel_r2_uClibc-0.9.32/root-ramips/etc/banner