I have just learn't how to transfer the GPX route to my Garmin and think its brilliant. First thing you need to do is register a Garmin connect account here http://connect.garmin.com/. The sites quite confusing so if you want to give me a call I can talk you through it in about 5 minutes.
I ran the Ridgeway back in September. The last 20 miles was probably the most difficult to follow and had the least amount of signs.