You could use a kml file, and the application "bbmaps" from BBMaps - BlackBerry
. Also Blackberry maps is able to import a kml file, but AFAIK you need your phone registered with a BES server.
(dont mixup bbmap with "blackberry maps" !)
I personally was not able to import a kml file into bbmaps but, that maybe because the sample I tried was to large. Try yourself (the programm is free to download and use)