If your mobile phone doesnt have GPS, as mentioned, the probably most easiest way to do GPS on your bike is to buy one of the 12 volt DC gps units off ebay, navsoon or the like, as they are the easiest to get maps for in either RPM for route66 software of .FBL for miomap/iGO software.
They either run windows mobile 5 or windows ce 4, which are really easy to use and to download free maps. Both allow for exporting and reimporting from google earth route files.
The last 4:3 navsoon i bought was around $150.... run a ciggie plug under your seat with an inline fuse from the battery and just remember to d/c ito stop your scoot scoot going flat...
Youd then keep the unit under the seat and bluetooth or wire the audio to your helmet...