A long time back, I removed all of the dust shields from the front end of the Celica (5-speed, 7AFE ST), while rebuilding the engine and restoring the engine bay. I let it sit like that a bit longer than expected, and now I can't remember where each one goes, where all the fasteners go, and what they fasten with. Anyone have a handy diagram or even some pictures of the shields in place and what they fasten with? Thanks!

I don't know the thread size off the top of my head, but open your hood and take a peek at the five screws holding your bumper cover to your frame along the top. Take one off, run to your local hardware store and buy like 50 screws that match. It's the only screw you'll need for everything down there (I'm assuming you mean the engine compartment's splash guards.
As far as pics, I dunno. I'll see if I can find something.
There are two big splash guards (right and left). One of them has a big opening for oil pan access. Just hold them up to the bottom of the car to figure that out - that will be the passenger side splash guard. The other will be the driver side. These splash guards also double as the wheelwell liners. You can just match them up to each fender and they should fall into place. All the holes will line up with the threaded holes in the subframe, don't worry.
The last splash guard is the smallest and it just bolts along the bottom edge of the bumper cover and the front edge of the subframe.