Heres a little online utility to help make custom j2me GpsMid midlets for your phone. GpsMid is a vector based tracker and viewer of OpenStreetMap data, I’ve covered it some more here, it’s rather good.
I like how you can search for streets and places, and it adds it as a virtual waypoint to help you navigate to that street. It also has good zooming support.
For my phone Nokia 6023i, I choose the no-obex option, and turn the routing off (it’s not quite working correctly for me).
Code is available on request, written with python, it’s designed to run the java conversion on the server. However, Java is quite memory intensive, and my host (dreamhost) hasn’t enough to run it. Offers glady received 🙂