I got a chance to mess around today, and here's how I got Orca AU running in Logic.
To get it to run with all of its presets:
copy "orca.component" to /library/audio/plug-ins/components
then copy the entire "orca" folder (the one containing presets, resources, and settings folders to the same destination: /library/audio/plug ins/components
*works if u copy to user/library/audio/plug-ins/components OR system/library/audio/plug-ins/components. whichever you choose, make sure both the orca.component file and the Orca folder mentioned above are copied to the same folder.
after that, a successful run of orca will create "fxpansion/orca/orca_preferences.prefs" folders in both your user folder and your applications folder. i don't mind the apps folder, but why the duplicate .prefs in my home folder? i'm fairly confident that it isn't supposed to do that =) maybe i still missed something?
Anyhow- do this, and Orca AU will load in Logic 8 on 10.5.5