There are a couple of places that have courses through the community colleges, usually as a benefit/incentive to industry. I'm not sure of a "summer school" course, but I know of two community colleges here in Wyoming that teach CNC programming as part of the course structure, and they are available "a la carte". But they are a full semester long, each. There are some really good books available that will tell you just about everything you need to be dangerous.
If you want I can tell you the name of the books and the author that I used in school and make copies of my notes (lathe and mill). We did one project a week for class using the lessons learned that week and our final was a program we wrote from scratch (long-hand g-code) that incorporated almost all of the different lessons into one. Sorry I can't be of more help! But let me know if you want a copy of my notes....
mgb I see you want to learn some cnc and you dont have the axcess for community college so i think. I also notice you are starting your own machine shop and you want the most help you can get. I was running A fadal and know I am running A haas mini mill if you need a any help I can also send some of my notes. good luck .
You can probably learn more reading on the internet than taking a class, assuming you have the discipline to teach yourself. My local CC offers a bunch of CNC classes... I took one and left after a few weeks because the pace was so slow. I learned the entire semester's worth of material in 2 weeks at home.
If it's CAD/CAM that you want to learn, try out one of those training videos like Mike Mattera's Mastercam videos. Again, you'll learn way faster if you dedicate your time and energy.
I have a training manual I made for a 160mc Fanuc. I also have my training manual I made for a Hurco. One is ISNC and the other is basic NC and conversational. My side job is training. I have trained at large places Automotive (Detroit), I have also trained in small 1 or 2 man shops. Usually when I was installing a machine. I sell the manuals. Here is my email firstname.lastname@example.org I am in the Indianapolis area. And I would love to go to California. My classes usually take 2 days for an Intro Class and 2 days for an advanced class (one on one instruction) I can train up to 4 but the class is 4 days. I would like to help. Let me know what you need or what types of questions you have. I will try to see what we can do just over the internet for a while.