ChickenBones linked me this.
http://www.chickenbones.crafts…I%201.1.3%20Hotfix%20.zip
It appears to be the submodule code he gave me, compiled for 1.2.3. Give it a shot.
Made an account just to let you guys know this fix works! I've been trying to get NEI working again on MC 1.2.3, this hotfix solved the 'crash when looking up IC² recipes' problem for me.
For all those other mod noobs (like myself) out there: the contents of the ic2 folder go into the IC² 1.81 mod jar. The Packager.class file goes into minecraft.jar.