I have decided to take a break from the world of IIDX AC reverse-engineering, mostly since I've figured out every scrambling algorithm that Konami has thrown at us so far. Here you can download the various information that I and others have gathered about IIDX AC so far. Hope you like C...

Source Code
crack2dx.c          Descramble .2DX (sound archive) files
crackeout.c         Descramble/rescramble DATA\INFO\EOUT.BIN (song index file)
crackgcz.c          Descramble IIDX DistorteD GCZ files (only DD has scrambled GCZs)
gcz2tga.c           Unpack a GCZ (texture) directory into separate TGA files [UPDATED]
packgcz.c           Assembles GCZ and IDX files from TGA files
pack2dx.c           Import BME charts into IIDX. UNFINISHED, DOES NOT WORK YET.
split2dx.c          Splits a non-scrambled .2DX file into WAV files
unz.c               Decompress .INZ and .XZ files into .INIs and .Xs respectively

Contributions and patches are welcome, but don't expect me to work on this stuff again anytime soon.

Have fun.