I'd like to present a new tool - called KFS (Kitserver File System). KFS is a user-mode file system application that provides a read-only "view" of original AFS content, combined with files from "patch" folders (called "roots"). This allows for simple run-time patching of game content, while leaving the original AFS files unmodified.
For those folks who used Kitserver AFS2FS module, this should look familiar. The important difference though is that KFS is a standalone application and is not tailored to any particular version of game exe, or any particular game, for that matter. Tested successfully with WE9LE, PES 2012 and PES 2013 DEMO. (Should work with other games that use AFS files, although i have not tried any)
The example of using it with PES 2013 DEMO is included in the kfs-0.2.zip archive, which also has detailed info on how to install and use the program.