Instructions
Launch NullDC.
Go to "Options" and then "Select Plugins." Select "Image Reader Plugin" as your plugin and then click "OK."
Click "File" and then "Normal Boot." An "Open" window appears to allow you to search for the ISO file you want to load on NullDC. Click the "Open" button once you find the ISO game file.
Click "System" and then click "Start" to load ISO on NullDC. Wait for the NullDC emulator to boot. The ISO game should play in a few seconds.