It's actually stupidly simple. You initialize the library which creates a file which gets mmap'd into your process. When your application crashes, the mmap'd memory is written back to the file by the operating system, and on startup again, the same initializiation routines bring the memory back at the same location. All the application programmer needs to do is check to see if the initialization recovered anything, and if so, set its pointers back up again. When I mentioned that the documentation for GTK-DOC was lacking, I was told to read the source.
People are so ironic sometimes.
There is newer documentation available in the package, including a Developer's Guide to give those interested in Recovalloc and idea of how to implement it. It'll be back next release. Until then check out the devguide.