The GUI method for mounting ISO's on the Pandora is the Gigolo application. I haven't tried this myself yet, but that's one of Gigolo's functions in addition to mounting remote shares. You may need to do this, before it will work properly.
There's vhba/CDEmu as well, but AFAIK nobody tried to bring it to the Pandora, yet. It's main purpose is to proper emulate a drive to reduce issues with copy protection mechanisms, so it's actually only needed for Wine anyway. But it supports multiple image formats that are not directly mountable like NRG, CCD, and MDS.