There's an access panel on the bottom between the engine and trans. You may have to unbolt the engine/trans mounts and jack up the engine slightly to access it.
Good luck. I HATE it when **** like this happens. A few days ago I was doing my motor mounts, fighting like hell to get the driver's side rear bolt started, when I dropped it. It didn't hit the ground, but I couldn't find it anywhere. I figured it was caught in the steering rack linkage, but couldn't find it, so I ended up disassembling nearly the entire steering rack. Still couldn't find it. After about an hour and a half I gave up, found a replacement bolt, finally got it started and got everything buttoned back together, lowered the engine back down, bolted it up, and low and behold...the ****ing bolt was sitting in the dish on the jack that was holding up the engine.