@Nahere: Even if you can't read interaction raw files, I assumed the interactions were described in the documentation, and if they are not, someone trying to shift them around presumably has learnt what they do, or the exercise seems rather pointless (unless it was an attempt of learning what they do, in which case they're out of luck...).
@Telgin: This script works strictly at the world tile level. However, the Region Manipulator
http://www.bay12forums.com/smf/index.php?topic=164136.msg7454345#msg7454345 can manipulate Mid Level Tiles (a.k.a. Embark Tiles) within the bounds of what DF allows. This means that it should be possible to manipulate the Mid Level Tiles within the embark world tile (pre embark) such that the tile in the middle of the embark belongs to a "safe" region, while the rest belongs to a reanimating one. I use that logic to create an embark with 9 biomes (the biome of the embark world tile, plus the biomes of the surrounding world tiles), although I use a custom script for that (and the world is a PSV world, so the world tiles have the "correct" biomes in all the 9 tiles).
The vanilla way to achieve this is to make an embark that's split into one non reanimating biome and one (or more) reanimating ones and place the fortress on the "safe" half/edge/corner, but I'm sure you know that (Showbiomes
http://www.bay12forums.com/smf/index.php?topic=160856.msg7194572#msg7194572 can be used to show where the borders are).
It's not possible to hack in-game tiles (the 2*2 meter ones) prior to embark, because they literally do not exist: they're created from some unknown seeds when embarking (or approaching with an adventurer, and discarded when out of focus again in the adventurer case).
It might be possible to hack in-game tiles after embark, assuming you obey DF's rules of which biome a tile belongs to, but I don't think there's any tool do do it. I know hacking these tiles work to some extent (hacking and placing farm plots on air tiles, to see what crops they can grow when investigating air biomes and anomalies in them), but I don't think there's been much research beyond that. Someone recently considered making a script that carried the surface biomes (and their boundaries) up into the air, but I haven't heard of any results.