Here is some handy information that was shared with me. It's also extremely useful for getting many other kinds of documents on to an iPad or iPhone. No need to Jailbreak!
Get set up:First, you need Readdle Documents. It's brilliant, you can throw virtually anything at it and it copes. So first download Readdle Documents. (TIP: Also try Readdle PDF Expert which links to "Documents." Readdle Expert gives more features than the basic PDF built in to iOS.)
Load the audio-books:
Step 1:From within the Documents app, choose Browser, navigate to jw.org and normally you can then download directly into Documents - audio-books, audio-magazines and videos all download into any chosen Documents folder. You can create new folders afterwards and move files around until you like the folder arrangement.
Step 2:Trying to download an AAC file directly into Documents doesn't work for some reason - instead it starts playing the file, which is rather frustrating. (If you know why, please comment below.) So the solution is this: First download the AAC file to your PC (or Mac). In the case of the new "Jesus" audio-book you end up with a 402mb file.
Step 3:Open Documents on your device, and within Documents, go to its Settings (the cog icon).
Open Wifi Drive and Enable (your PC and device must be on the same wifi network for this to work).
Note the URL shown below it in small text, (i.e.: http://192.168.1.102 - this is your device IP address).
Step 4:On your PC (or similar on Mac) go to "My PC," and choose this IP address (if it already exists) or set it up (using Add Network Address).
Double-click on this (then be sure to 'Accept' when the message pops up on your device) and, after a minute or two, on your PC you can now see the whole folder structure of the Documents App on your device.
Step 5:Navigate to the folder you want, (or create it), and then drag the AAC file from your PC into your device folder. It will now copy across wifi. (Note: For security, when finished all copying, disable Wifi Drive in Settings.)
TIP 1: You can easily create folders and move files around in Documents afterwards, but better still, in Settings, File Manager, set Download Files To to "Ask for Directory", this allows you to choose where a downloaded file goes to, rather than have to move it around afterwards.
TIP 2: Sometimes the PC won't recognize the device IP address. If so, within Documents, go to Settings, Wifi Drive, and set up a username and password (anything, it can be a one-off temporary one), and try again. This usually solves it.
DONE!Now the AAC file for the "Jesus" audio-book plays perfectly within Documents on your iPad.
You can use this method to quickly copy all sorts of documents and files between different devices. Once they are in Documents, you can often choose to open them in other programs, rather than Documents, using the upload and download arrows at the top of the Documents window, which then gives you many options.
Have fun! Please let us know how it goes in the comments below.