Turn by Turn Sat Nav for Windows Mobile 7

I would like a turn by turn sat nav application for use on Windows Mobile 7 OS. I would like it to have the same functionality as CoPilot <[login to view URL]> I guess using Bing maps for the route navigation would be best? I will require the Vworker to outline in detail how they are going to develop this sat nav system, including technologys used etc etc. This outline will be needed at the bid stage, any bids without explanation will not be considered. At the moment I am just trying to gauge how difficult this is to produce.