Fan translators, general-purpose modders--the wait is over. Enter AT7View, a modding suite for the AT7 container format in the Pokemon Mystery Dungeon WiiWare games.
Download latest release here
Source code and how-to guide here
Decompression, recompression, file extraction/replacement, all the fun stuff's here. Maybe even more to come in the future, like a texture converter, a table editor, or a recompressor not built around my trash coding skills as of now.
Just wanna give a huge thanks to Platinum Lucario and MegaMinerd for their AT7 container research. Couldn't have made this without it.