*Solution created by ZeroThreshold from the Xbox360 version of this game*
If you wanna do this solo, turn on a second controller (I'm not sure if it has to be signed into a profile, but to be safe, I'd say do it) go to the simulator, and just replay an HQ mission. I always chose HQ: Stark Tower 2. When the mission starts, head to the "Next Mission" console, which will take you back to the simulator map screen. Just keep repeating this over and over, and you'll get it in no time at all. Worked for me. :)