Without knowing how much current will be drawn away from a bridge point, you can't compute the resulting voltage at that point. If you have data about the input impedance of the CCI port to which your bridge will be attached, you can factor that into your bridge calculation. The other option is to get the voltage divisions close, hitch up the interface and a voltmeter, and trim to get the proper division for each switch position. At least, voltmeters are designed with high input impedance, so when you take it away after trimming, the voltage will still be quite close to what you want.
P.S. I like the way you disguise the "math" in your post.
