Applescript Control of System Services

I am completely confused. I've been Googling for a few days, but I haven't been able to find a way to interface Applescript or Automator with system services.

The reason I want to do this is that I have an application (GraphViz) that has a system service associated with it, but apparently no AppleScript dictionary. I would really like to be able to automate it, but right now it's beyond my grasp.

So is there a simple way to do this, or?

 

Indeed -- it doesn't have AppleScript support. That's why I'm trying to use the service. Of course, that's a pain in the ass, so I was wondering if I could call a service from a script.

I can do it through GUI scripting, but I thought there might be a nicer and easier way to do it. Guess not.