blkfrd,
If you really insist on doing this I would suggest a circuit with an op amp driving a discrete push-pull stage. The ammeter in series with a 1 Ohm resistor from the push-pull output to ground. You will need dual power supplies. The op amp can be configured with the feedback coming from the push-pull output stage and resistor to set the gain and it will then read 2 * g volts full scale.
Bob