Can I use a digital multimeter as substitute for a zero resistance ammeter?
Yes, using Ohm's law: I=V/R.

The only true "zero" resistance ammeter are superconductive. In practical use, the voltage drop across a small resistance is measured. If your DVM can measure down to a millivolt (mV), then a 1 mV drop across a 0.001 ohm resistor shows a flow of 1 ampere current. You'll need to consult the guide (~$45 online) for the maximum permissible voltage drop, and use an appropriate resistance.

Recently, I used the voltage drop across a piece of #16 copper wire to measure currents in the 1 to 5 A range... a switch in the circuit had greater resistance!