I have just created a Garmin map with the Openstreetmap data. You can preview the data available by browsing the Openstreetmap map : OpenStreetMap
You can download the map here : hhttp://fredericbonifas.free.fr/osm_civ/cote_divoire_2011_06_03.zip
To install it : Plug your GPS unit in mass storage mode, create a folder called Garmin in the SD card and put the file gmapsupp.img that you have downloaded into this folder.
I know that many roads are still missing. Uploading your GPS tracks to Openstreetmap, or sending them to me directly is the best way to see this map improved.