I have never done this, and do not have time to try it, but if you have both AutoCAD and AutoCAD Architecture installed on a computer and you have run both at least once (so that the secondary installer has run for both, copying the files that it does to your Windows profile), you may be able to export an AutoCAD Architecture profile and then, while running AutoCAD, import that profile into AutoCAD and make it current. That should get your main CUI flipped over to ACA.cuix. If that, in and of itself, did not load the ACA ARX modules, if you try to run an AutoCAD Architecture command, and your AutoCAD Architecture profile has Demand loading of ObjectARX apps set to Object detect and command invoke (Options dialog, Open and Save tab, ObjectARX Applications area at the lower right), that should get the appropriate ARX modules loaded.
If that works, post back and confirm it for others.
David Koch
AutoCAD Architecture and Revit User
Blog | LinkedIn
