I am posting these instructions in response to a recent tweet and the occasional mailing list query.
Upon first launch of Little Snitch, it is reasonable for a VO User to assume the app is not accessible because it is not possible to locate or interact with any parts of the app in it's default setting; however, , much of Little Snitch is actually quite accessible if you can find someone with enough sight who can spare a few minutes to tick a single checkbox within the app. I’ve included instructions to do this below.
Note that this is neither a review, an endorsement nor an app entry for Little Snitch. If you want more information on the app, it is available in droves through your favorite search engine.
Also note that this app is not a toy. This is a firewall and misconfiguration can create serious communication problems on your Mac. OS X comes with good firewall capabilities already enabled, and they are sufficient for the vast majority of Users.
The initial installation process for this app is accessible, but I strongly recommend not installing it unless you have enough sight or have a sighted person available to enable VO access by performing post-installation steps 2 through 4 below. Until you've enabled VO access for this app, it is possible Little Snitch might start interrupting network communications with no way for a blind User to know what is happening or to independently reverse the firewall behavior.
The following installation and configuration instructions assume Little Snitch version 3.5.1 and Mavericks 10.9.5. The app is supported under Yosemite, but I've not tested it.
1. Install Little Snitch and restart the Mac when prompted.
2. Launch "Little Snitch Configuration.app" from the Applications folder.
3. Open the Little Snitch Preferences.
4. In the Security tab, tick the checkbox labeled “Allow GUI Scripting..” This is the step that will enable VO to interact with most parts of Little Snitch. You might need to restart the Mac again at this point in order for the change to take effect.
Once you've enabled GUI scripting, you should find that most important parts of the app, such as the popup notifications, the details, radio buttons, checkboxes and other elements within those notifications, the preference panes, the rules table and editor, and the menu extras, are accessible to VO. One part of the app which I’m pretty sure is not VO accessible is the Network Monitor screen.
HTH, YMMV and caveat emptor.