I grabbed this 10mm hex socket for $1.97 at my local Home Depot. Worked just fine.The specified torque value (at least for a 2005 V6 Camry with the U151E transmission; others probably similar) is 36 ft-lb. I got mine leak-tight with an inexpensive Harbor Freight click-type wrench (advertised accuracy of +/- 4%, but who knows how accurate it is when it has not been backed off to zero for storage?) set to 35 ft-lb. The how-to recommends using hex sockets, which are not common provision in DIY garages, but are worth getting for this job.
In my initial attempt, I tried to use hex keys (!) and although I got the bolt off successfully, I could not tighten it enough (lever arm was insufficient) and had a leak.
There is a lot of Web reading you can do on the accuracy (or, more precisely, lack thereof) of torque wrenches that will make you despair of getting a DIY car repair job done properly if your idea of correctly performed work includes meticulous observation of FSM torque values. Personally, I pull out a torque wrench when I want to increase my chances of not under- or overtightening a fastener, but in the price bracket where I buy torque wrenches, it is about adjusting the spread, not shooting for certainty. Obtaining and maintaining high accuracy is expensive and very few applications (such as engine fasteners, as Hardtopte72 alludes to--anyone remember the Cressida head gaskets?) justify the cost.
If you are unsure about the accuracy of your torque wrenches, this digital torque adapter is a great, great tool to have to calibrate them at home.
The easiest way is to clamp a socket into a bench vise, attach the digital guy to it, then set your torque wrench somewhere in the middle of its range and see how far it is off over/under. The digital adapter comes with a calibration certificate so it should be pretty darn accurate. I got this with a 3/8 inch and 1/2 inch all from Harbor Freight and out of the box they both were under by 3 ft. lb. and 2 ft. lb., respectively according to the digital.
... and I don't have a bench vise so I sunk a 6 inch hex head lag screw and a washer into my work bench and tightened it down as much as it would go. Now I just slap a socket on top of the screw, then the digital adapter, then my torque wrench and I can tell how far it is off.