The two switches uncovered the 4 glowing power stabilisation things on the outer wall near the bottom platform. Throw some grenades into each of them.
Once all four are destroyed, they cannot stabilise the enormously powerful energy beam being sent down from a geosynchronous satellite, if the beam should become unstable... Be prepared for a twist that turns this from a merely "very good" mod into an awesome one!
P.S. There is no need to cheat (I see your pheremone pouch!), just put the difficulty on "easy" (which is the equivalent of "normal" on most HL2 games). There is ample ammo/health/armour provided...
