To implement a new driver you need to create a new module in web/session/drivers/ with the name of the driver as the file name and .py as the extension.
The file should define two classes named in a similar way to the database driver classes, one of which implements the checking, creation and removal if the driver environment and the other implements the web.session module API and inherits from the first class.
The web/session/drivers/database.py can be used as an example. If you implement all the methods in the same manner as the database driver and each method returns variables of the same type in the same order and raises the same extensions you will have a valid driver.
Please forward any such drivers to the developers who may wish to include your driver if it is of a sufficiently high standard and does not require any API changes to any of the other web modules.