Short usage:

Under UCI:
Copy all files (including learn.book !) to the same directory and install it in your UCI gui as usual.

Under WB:
Copy all files (including learn.book !) to the same directory. Set EGTB path and hash in snitch.ini.
Use the -xboard command line parameter to execute snitch:

snitch.exe -xboard

Remarks:

Book learning is disabled by default.
Do not delete learn.book to make sure no learning will occur. The default book alone is to simple to really help.
If you don't wan't snitch to use its own book, delete both books.