Writing the image to the SD card using just an ipad would possibly be problematic. I don’t know off the top of my head any apps that can flash images to SD cards; let alone do the initial bzip2 decompression on the file. That’s another thing! Probably would be better off either using a friend’s computer, or dare I say it; going to an internet cafe.
If you do want to use just your iPad, you can set it up as a wifi access point, and connect your gameshell to it that way. The app I personally use when doing this is “Pisth.” It’s a paid app, but its what I’ve used for other devices in the past, and what I’ve had luck with. (I have no affiliation with them, so hopefully this doesn’t sound like an advert!! Remove this if needed mods)
Technically you can use the game shell out of the box, but you’d have a lot more fun with a more current modified operating system.
Here’s a link to some (hopefully) simple instructions on how to flash an image, using a mac or really any computer. Just replace the file name and size stated in step one with whatever the one you’re downloading is. 
Another side note: The custom DEOT image will also automatically fill up all of your SD card’s space, but will need to reboot a few times, but only the first time. Don’t panic! This is normal, and it will be up and running, taking all of your SD card’s space. This will save you the step of having to open up a terminal command line, and typing in code to fill up the unused space.