i picked up a little dental mirror at wal-mart the other day for this purpose. it was in the pharmacy section, bundled with some plaque scrapers i might be able to use for something else.
these links have pictures of the indentation you are looking for on the area just outside the cam seal. it is near the top, slightly toward the back of the car.
http://www.toyotanation.com/forum/t109966.html
this one shows it in the 4th picture, circled in green:
http://www.baktasht.com/_html/hosted/timingbelt4.html
you should really get yourself a replacement timing belt cover and borrow a timing gun. try a local salvage yard or looking on
http://car-part.com/. it won't be possible to get tune your timing right without it. you may be able to get it to turn over on it's own, but you will be wasting fuel and it will probably overheat the pistons and cause carbon buildup which will eventually ruin your piston rings.
that said, yes, you want the first piston at the top of its stroke. when this is the case, the tab on my crankshaft that keeps the belt pulley from spinning is pointing generally upwards.
the reason it will be hard to get precise timing is that the piston doesn't move very fast when it is near TDC. it moves quite fast a quarter turn later, so you could find the middle of the stroke with some precision, but not TDC because 5 degrees of rotation will have a much less perceptible impact on the depth of whatever you stick in the spark plug hole. also, it's easy to damage the spark plug threads and screw up your torques if you use a heavy rod, and it's also easy to break off a chunk into the cylinder and damage it when it's running if you use a wood rod or something friable or dirty.