I have a '97 Camry 4-Cyl that is probably similar. Yes, the valve cover is removed with the big nuts on the spark plug tunnels. Mine are metal, but they should unscrew rather easily with a large-jaw wrench. In fact, if they are loose then simply tightening them could fix the leak. Tighten each one a little and wait a few minutes and then do it again to slowly compress the gasket evenly. Unfortunately, my Camry's valve cover leak was a little deeper. Just below the valve cover gasket, there are 2 semi-circular metal plugs in-line with the cams. I think the head had to have cutouts so that they could bore for the cams - not sure. Anyway, the semi-circular plugs that fill these cutouts in the head are held in and sealed by a special black adhesive that you get at the dealer. It is common for the oil leak to be around one of these plugs, and the best thing is to get new plugs and the adhesive and replace them. Also get a new valve-cover gasket. The best thing to do is go to the parts dept at a Toyota dealer and have him show you the schematic setup on his computer. The semi-circular plugs are really cheap, but you many have to order them. The adhesive is expensive at about $14 per tube (and you will use about 10% of it). I think that the valve cover gasket is about $11 or $15 - can't remember.
Make sure everything is clean as you take off the valve cover. Take it to the car-wash beforehand or spray around it with brake cleaner.
Hope this helps.
