Just discovered that /Map folder in the SD card works as well (so long as it is in the root directory i.e. at the same level as the /Garmin folder). I decided not to have any maps in the internal memory and moved all my maps to my 8GB SD card leaving only the JCV files and basemap in the Internal memory. I now have more than 10 maps in the card and still plenty of memory capacity left. All the maps are available for selection through Tools>System>Map>Info. Very neat feature.
NOTE: This is for those who wish to store multiple maps into the SD:/Garmin folder that will also have jcv and lane assist whose files are stored in the SD:/Garmin/jcv folder. AND also for the brave trying something that may possibly brick their unit
There is the GarminDevice.xml file in the main memory:/Garmin folder that determines what file names, path, I/O etc in the device. Notice that you can put maps in the SD:/map directory but the maps will NOT have jcv or lane-assist. This also for maps placed in the Main:/Garmin/map folders. Unfortunately, only a max of TWO maps at a time can currently use the jcv files and it must be named gmapsupp.img. placed in either of the /Garmin folders. POSSIBLE SOLUTION ??
Use a text editor and look at the GarminDevice.xml file: The NMaps xml format does not have a BaseName slot. Thus the SD:/map folders can take anyname.img. Now if you want to put multiple maps into the SD:/Garmin/ folders with anynames.img using the jcv files in your 8G SD:/Garmin/jcv folders here's what you do: Within the SupplementalMaps remove the <BaseName>gsuppmap</BaseName> characters in the xml file. Now the SD:/Garmin will be like the Nmaps, taking any names. You can now store all your unl files in SD:/Garmin with other multiple maps there and it will use the jcv feature. And you do not have to touch your main memory pre-installed files (except this file!!)
Anybody brave enough to try and come back from the dead? Just be v careful - remove only those characters above at the correct location and type carefully. Otherwise you have no device and the usb comms will fail!