I have an irrigation system that I need to winterize. In the past I
used to hire a guy who installed the sprinklers but since I already
have the compressor and everything else I need, I'd rather save $70.
I've seen him hook up the compressor somewhere on the back low but I
don't know where. I was hoping that someone would be able to tell me
where to attach it and if there is anything else special I would need
to do.

Here are some pictures of my backflow:

http://www.medicfamily.com/tmp/DSC02319.JPG
http://www.medicfamily.com/tmp/DSC02320.JPG
http://www.medicfamily.com/tmp/DSC02321.JPG

Thanks!