At this point this texture pack is out of date. So it won't work correctly with the current version of JJ.
But for future reference -> viewtopic.php?f=21&t=2776 You can't change textures on iOS 6, unless you're jailbroken.
1.Junk-Jack-Wiki 2. The world is big, 256 blocks high and 768 across. 3. Who is John Galt? 4. Lack of objection does not indicate consent. 5. We scream, we shout, we wail, we cry; but in the end we all must die.