I did it for a while in google earth. The results were ok, but it was a PITA. I discovered Mapmyride, which is a huge improvement in concept, but is pretty buggy. RideWithGPS is similar and has fewer bugs, and is what I use now. It has gotten better since I started with it, and I suspect the mapmyride has too. With both you just need patience and the ability to devise workarounds. Part of the problems are not with the programs themselves, but with the less than perfect, and frequently changing public databases they access.