||I work with CAD and GIS on a daily basis and I echo the last poster's sentiments. Arbitrary coordinates don't translate well into GIS.
The only way I know is by trail and error. I "drag and drop" shift, tweak and whatever it takes to get the most accurate positioning. Most of the time though it won't be precise.
Its not an ESRI issue, its a survey methodology issue.
I actually state on every map that includes AutoCAD overlays (developments in this case), that the map isn't a precise indicator of where the development lies in the real world, however it is relatively accurate with respect to mapped features.