Well, now that I think about it, this won't do the trick either.

This perfectly would provide the necessary 12v-->6v translation. But the circuit would also need to perform 6v-->3v.

Per your schematic, the "input voltage" to the LM317 isn't alwasy 12v. It's sometimes 6v. Reguardless of what the voltage is, (12 or 6) it must be divided in half.

Hrmmm, close tho!

Thanks