Since I treated myself to all the parts, I thought I would fix my leaky valve cover gasket and timing chain tensioner while on vacation. Here is a step-by-step DIY, and I've uploaded several pics that hopefully will help others with the same tasks.
Timing Chain Tensioner - Toyota Part 13540-0D010
Valve Cover Gasket - Toyota Part 11213-0D040
Permatex Ultra Black RTV Sealant (but you can use other sealants)
Note: I have a 2001 Chevy Prizm but I buy interchangeable parts with a discount at a local Toyota dealership. Also, the Chevy dealers rarely have the stuff on hand so I don't bother. Toyota always has the parts in stock.
Tools I Needed:
3/8'' or 1/2'' drive ratchet
1/4'' drive torque wrench
10 mm deep socket (or regular extension bar)
10 mm socket
10 mm reversible ratcheting combination wrench (RRCW for short)
19 mm socket
jack and jack stand (optional)
1-3 hours, depending on skill and speed
These instructions are general guidelines only and may not apply to your vehicle. They worked for me. I assume no responsibility if these procedures do not work for you.