By default, you should simply be able to add the YAAF directory to the Codewarrior Path using the Edit|Project Settings dialog box.
If you are interested in rebuilding the YAAF libraries, it's a little more complicated.
There are three versions of the library: one for the MacOS 68K, one for the MacOS under PPC, and one for WinOS Win32 API.
There are also two different libraries: the YAAF_Core library which provides the core event loop, window processing, and other basic features. And the other, the YAAF_Ctrl library, which provides different controls, such as buttons, scroll bars, and the like.
I hope, by the way, to continue developing these libraries in this direction: with new views and other features built into a separate library. This helps keep the code manageable, instead of lumping all the new functionality into one gigantic monolythic framework library.
Anyways, the source code for each of these versions are all in the (Sources) folder. The 'Core' folder contains the core library, and (mostly) is built using the same files with the occassional OPT_MACOS and OPT_WINOS conditional compilation flags. To build the libraries, you need to recompile each of the different project files.
The source code for the controls are in the (Sources):Standard Controls folder. Like the core, they are mostly the same source files, but conditionally compiled.
There are three custom resources used with the Macintosh version of the library, and one custom resource for the Windows version. Two of those three custom (Mac specific) resources are the 'MInv' and 'MCmd' resources--their templates are stored in the ':Resources:ResEdit Templates' file. If you wish to use these templates, you need to install these two templates into the ResEdit preferences folder in your system folder's preference folder.