"Adding the recovery partition needs to be done at the command line because Disk Utility at the GUI won't permit creating a partition as small as the Recovery Partition, nor will it hide the partition properly."

This is not completely true: Disk Utility lets you create small partitions, you just need to type the partition sizes in the text fields (it won't work dragging the division bars in the graphical representation).
That said, it's true that you cannot specify the partition size down to the byte (but this is not so important, it suffices to give a partition slightly bigger, eg. 0.66Gb, and the image restoration will work the same), and you cannot specify the right partition type neither hide it, so it's definitely easier to use diskutil from the command line.