Find a trusted source (e.g., Reddit’s r/roms megathread). Download the game as a .rar or .7z archive split into multiple parts (e.g., .part01.rar ). Use to extract all parts into a single folder. The result should be a folder containing default.xex and a data or content subfolder.
In many jurisdictions (e.g., USA under the DMCA), circumventing DRM via RGH is illegal even for your own discs . However, downloading a game you already own is generally considered a “gray area.” Distributing copyrighted games is clearly illegal.