Part I - Overview provides a quick overview of G-Cows; this should help you to decide whenever it fit your needs or not.
To quickly grab your hands on G-Cows use Part II - Tutorial; G-Cows is a simple tool and starting working with it is probably the best way to learn it.
Part III - G-Cows: architecture and language provides a complete description of G-Cows and a reference to all functions.
As you probably supposed, English is not my native language so this will never be a well-written document.
Use of terms G-Cows, Cows and Cows-mkgen throughout the manual can be confusing at first so let's see the convention used.
G-Cows is the name of the whole package; we'll use it when generally speaking about the project.
Cows is name of the scripting language and the language interpreter.
Cows-mkgen is another program included in the package.
To add more confusion, Cows and Cows-mkgen are capitalized (since they are names) but in examples and sample code we'll always use their invocation names, which aren't - of course - capitalized: cows and cows-mkgen.
This manual can be downloaded from http://www.g-cows.org/.