How to Update Rosen Nagivation Software?

There is a lot of information out there on the Rosen installs and the systems strengths and weaknesses; however, some of the navigation weaknesses can be made better with a change in the navigation software.

Anyone who has successfully changed the navigation software, can you please post a how to? Garmin, TomTom, iGO, etc are all possibilities, along with adding TTS.

Anyone with experience in this, please help.

So far, best source of actual software seems to be found in the link from the post "Rosen Nav Ups and Downs". I would post the link but I can't since I don't have 5 posts yet (sorry).

Again, no instructions for the next step. Any help will be appreciated. Thanks.