Unless someone is pretty familiar with the MRC 6200, it's a pretty hard question to answer.
Well, if you have a DC powerpack, the output polarity varies based on direction, which is why there is no polarity indication! That being the case, you'll really need to go inside the powerpack and connect the amp meter before the polarity reversal switch in order to get a good current reading. As for the volt meter, I'd probably consider a Schottky diode bridge to correct the polarity and monitor the output terminals. You may be able to also connect it before the polarity reversal, it's all dependent on what's in side your MRC powerpack.
If, as I suspect it is, wired like this MRC powerpack, the red & green arrows would be where to connect the voltmeter, and the yellow circle would be where the ammeter would be connected in series with the output wire. It appears that the direction switch on these powerpacks comes after the voltage control.