Okay here's how this is done.
1. Load up the mission Dispatch.
2. Play on RECRUIT this will make it a total cake walk. I absorbed so much damage and still won.
3. All you really need to do is head right for the objective kill ALL of the drones and turrets.
4. Troops seem to respawn unless there are just dozens of them so don't worry too often about them but obviously gun them down if they look at you funny.
5. Plant the EMP and DEFEND it or you will have to replant it.
6. When it goes off simply walk up to the drop ship and the chairman will die in a scripted event, hooray for realism.
Video below showing how easy this will be as recruit turns you into some kind of bullet sponge.