Very elegant as usual Mike, and if start up were a problem a boost circuit is easy, I am not sure that the transistor is driven from a port pin, else pwm should be practical.
the only other requirement seems to be a three volt setting .

"The problem with a single regulator is that it won't work for me. I don't have access to the transistor side. I have two "lines". 12volts...and the collector of the transistor.

The input voltage is controlled by the circuit. The motor is opperated with an onoff as well as it has two "speeds". 12 volts and 6 volts. I need to change this to 6 volts and 3 volts "

Now that might prove tricky as we need a selector scheme. For long term reliabile starting at three volts a boost scheme will be a must.
I was thinking of strapping a regulator as a constant current source , but that only works for well defined loads and motors with low inrush designs.

still this is one to add to the sneeky ideas list thanks Terry