The Application tab – it's not really a tab but I don't know what else to call it – of the Application Preferences dialog lists various folders that AutoCAD for Mac searches for support, driver, menu, and other files. This is the AutoCAD for Mac equivalent to the Files tab in the Options dialog on the Windows version of AutoCAD.
On the Windows version, adding a new folder to the different search paths is pretty straight-forward: select the parent folder; click Add...; click Browse...; select a folder; done.
In AutoCAD for Mac, that process is a little more elusive and on the surface, looks like it can't be done at all. It can … but it requires a trick, as documented in the following solution:
Using the steps described you can create a new entry in a search path and then browse to select the folder you want to add. It's only a couple more keystrokes but it's better than having to manually type something like:
/Users/Tom/Library/Application Support/Autodesk/roaming/AutoCAD 2011/R18.1/enu/Support