Hello Nigel,
we developed a board with the MCF54450 and only one DDR2 - chip. At present we use serial and parallel termination. Using only the serial termination with the address lines seems to function, what we did not test intensively however. With the data lines the ODT of the DDR2 - chip can be used for paralell termination. Set simply OTD enable to High (1.8 V ). The Coldfire does not support that, but with a single chip one can switch the internal termination simply on manual. Ths should save a little bit of space and money. A 0.9 V regulator will be in any case necessary.
Greeting, Markus