Your friend could use the assembly instruction manual (AIM). It shows the hose routing and color codes.
I'm sure he could.. but if anyone has atleast 1 page with vaccum info for the emissions ect. I could print off for him that would be helpful. I know I've shared many diagrams in C4/C5/C6 forums over the years... Since that is what I work on mainly, I am not really a big help to him with service info, but would like to try to help him out if possible without waiting for or paying for a manual.
Here's a photo of a base 72 engine.
1 small hose from the vapor canister to a nipple on the front of the carb.
1 large hose from the vapor canister to the pvc valve and then to a nipple on the front of the carb.
1 small hose from the distributor can to the TCS solenoid and then to a nipple on the side of the carburetor. The third port on the solenoid has a small foam filter on it.
Hope this helps!