User blog comment:Mrob27/Internal Data Format/@comment-5144400-20120806184458/@comment-4583259-20120807212455

I've never tried to do anything that ambitious. I've never even changed individual blocks and tried to put it back on the iPad. All I've ever done is to replace a whole file with older versions of the same file. I did this once to fix a friendly astronaut infinite shooting bug by eliminating all the astronauts (I think I just replaced all the dat files). Then I told iTunes to restore the iPad from the backup, which is a tedious process and also blows away anything else on the iPad that wasn't in that backup, so it's risky.

The mobs are in the ".dat" files, but aside from finding some credible evidence for what the coordinate format is, I didn't investigate any further. The type of mob must be in there, and I think the easiest thing, instead of hacking the file to "spawn" mobs, would be to just place some Mini_Lights, and edit the file to change them to Blue_I's.