Below is a "Paper" (Guide) on how to achieve on PPSSPP for Call of Duty games.
Short Descriptions (SEO/snippet)
If you see a file labeled "Call of Duty Modern Warfare 2 PSP ISO" – it is almost certainly a homebrew mod (a fan-made map port) or a virus . Stick to the official PSP titles listed above.
Q: Is it safe to play Call of Duty: Modern Warfare 2 on PPSSPP? A: Yes, it's safe to play Call of Duty: Modern Warfare 2 on PPSSPP, as long as you download the game files from reputable sources and use a reliable emulator.