Not sure if this will help you in your situation by others maybe interested in this. I have an aftermarket Kenwood indash nav system in my car which uses Garmin as the navigation engine. I am able to load geocaches into the unit so they appear as icons on the nav screen. I am able to select a geocache, retrieve all the cache information, and even get turn by turn directions to navigate to it though I have to be careful as if the cache is off road it will route me to the nearest road closest to the cache. It does work good for urban caching. To get the cache information into the Kenwood requires GSAK and the Garmin POI loader which allows me to load complete PQs. The key here is the indash nav system use the Garmin for the GPS unit.