Yes! Most GPS units can save point and line data (usually called Waypoints and Tracks). Utilizing the software that came with your GPS unit, you must convert these data into a .GPX file. Garmin, for example, makes software called BaseCamp that will do this.
Each map in LANDSCAPE has an Import button. Press it and you will be presented with choices for the type of data you wish to import.
Choose the .GPX option, select your file, and click Upload.
Please note that the map you are viewing in LANDSCAPE must support point or line data. The map in a Tract editing window, for example, only supports Polygons, so no data can be imported from a .GPX file into this map.