If you look at the properties for the deskotp shortcut created by the installation of ACA, there is a string of text like so:
Code:
/ld "C:\Program Files\AutoCAD Architecture 2008\AecBase.dbx"
That is the function that loads all the ACA tools. Outside of that, I'm at a loss as to why you want to do what you're doing. I understand you want a vanilla autocad interface with ACA tools, but my thoughts are that you are going about this the wrong way. It took them years to finally get the arx functions fully seperated from each other. Before the 2006 release it was very difficult to keep the tools seperate which really caused problems for those using ADT as vanilla AutoCAD when they tried to share with others who only had vanilla acad.
If you want ACA functionality, but want the interface to look like AutoCAD, get into the CUI, load the Acad.CUI as a partial in the ACA.cui and set which menus/toolbars/shortcut menus you want to see in the workspace and run from that. As always, when messing with cui files and such, back them up before changing stuff.