oil leaking at one of the screws on the valve cover

I don't have a published procedure for removing the valve covers on your car. You need to use your eyes and logic to remove whatever is necessary for access and be careful about how you reseal the gaskets because valve cover leaks are a nuisance problem and it needs to be done right. If you want to do this job because you want to learn, get a friend who has some knowledge to help you. If you're trying to save money, and you have to ask for instructions on how to do a job like this, you're better off paying someone else to do it right and not risk problems with the job or your engine. My recommendation is to take it to a Toyota specialist and get it done right and not create problems for yourself. Here's a directory link for you: http://repairpal.com/toyota-repair-in-harrodsburg-kentucky