How do I...

I don't know if you can add a via point with that model, but if you can just add one on the route you want to take.

If you are driving, simply go the way you want to go and that will force a recalculation.

According to the "manual" (and I use the term loosely), you can touch the text bar at the top of the map screen to open the list of turns, so you can review the route that way. To force a recalculation if you don't like that route: the only way I know would be to add a via point that lies along the route you prefer. The Nuvi will then calculate a route that takes you first to the via point, then from there to the final destination. But that still doesn't guarantee that it will calculate the same route that you would choose, just that its route will include the via point. Unlike most handheld gps's (and some auto units), the Nuvi 200 can't download a route that you've set up on your computer, so you can't tell it exactly which way to get you to your destination.

Drive it the way you would like to and it will Recalculate. It may tell you to turn around..But you could also tell it there is a Detour.
There really isnt anyway to set your own route in anything below a 700 series Nuvi.

True, and this is especially handy if you know how to get to the city (for example) and only need the GPS for the last few turns. Just go the way you want, and ignore the GPS until you get to unfamiliar territory.

Yeah, I do the same when I travel sometimes. I select the major roads that I want to take and leave my GPSr out of route mode. Then when I get closer or want to see how far I have, I then put it into route mode.