A quick check on the script aubrsync also contains rsync however it does not contain umount, but it does include 'remount'. So I suggest you still use aubrsync. What you need to do is to manually copy 'mount.aufs' to /sbin, aubrsync to /usr/bin, since your 'make install' has failed. There is no need to 'umount' before you 'remount'.

If you want I can post you my compiled aufs-utils. But it was done for kernel 2.6.38.7 which I am not sure it will be compatible with your kernel.