Your voltmeter can simply be connected to the PWR-56 output or the track somewhere.
For the ammeter, you want one that measures in amps, not microamps, with a range up to 5 amps. Ammeters require a shunt. A shunt is a high power, very low resistance, high precision, wirewound resistor. This may be built into the meter or it may not. Most likely not. The shunt is placed in series between the + output of a PWR-56 and the track. The ammeter is then placed across the shunt leads. Meters often indicate on the backside the shunt resistance to use. No two meters are the same as the shunt resistance is a function of the coil resistance inside the meter.
