So, dogtail is huge. Really, really huge. So huge, in fact, that I'm a little bit opposed to trying to wrap my mind around it, especially since it has a bit of a documentation problem. As such, I'm going to stick with playing around with guitest until I get a response from the GUITAR guys.
Back to guitest, it would appear that a vast amount of functionality stems from this little nugget. It looks like the way guitest works is by hooking pretty much any GTK call you could ever want to make.
By the way, if anyone knows of a way for me to copy code out of TextMate that retains the syntax coloring, please let me know (extra kudos if I get it in HTML format).