Info on the mvs source volumes

I am thinking about modifying the the MVS3.8j source and have been unable to get a handle on what needs to be done to compile MVS.  Googling doesn't seem to move me forward so I was wondering if there is perhaps an early 1980's book that delves into the OS building process or internals I might try to find on ebay or where ever.  Any web resources that anyone knows of would be appreciated.  Thanks.  Buddy