You said "route"..... Are you trying to save it like a "route" versus a "trail" like we typically use in desert? I know I'm probably over thinking it, but I just want to clarify as they are typically very different...
What platform are you trying to end up at? Going to an iPad? or???
Or have you already got this figured out and done?
I was just creating routes on google maps, Exported to KML, then used GPS Visualizer to convert the file to GPX. That file I emailed to myself and opened on my iPad using MotionX. To get the GPX file to USR for Lowrance I used GPS Trackmaker.