I don't specifically know about the 2002 but i Just did it for a 2001
Remove that black rubber around the radiator by pulling it up that rubber piece comes in two different pieces after you take out the 4 bolts that's holding it together with the radiator. You might have to go under the truck and remove the mud guard to take one of the rubber piece that I was telling you about which is connected with the radiator once you take that piece out now you could pull that rubber piece up now. Don't forget to disconnect the battery before you proceed to the next step. You will need 14mm, 10mm, 12mm sockets etc...
The special bolt to release the tension or the tensioner is located directly on the bottom of one of those pulley loose it up to release the pressure on the belt, require a 14 mm socket , ratchet and an extension to make it easier. Putting it back require the same step but in reverse. Don't forget to draw the diagram of the belt.
if you can't take out that rubber piece take the top hose of the radiator and unscrew the radiator holder lift the radiator that is just another way to remove it . you need to remove the antifreeze from the radiator prior of removal. That's one of the reason I subject strongly by trying to find that little rubber piece to remove first it will make it much easier, faster and less messy.
To remove the antifreeze from the radiator unscrew that little white plastic thumb screw with your hand located on the bottom left side facing the truck or the passenger side.
An alternative way is to jack up the passenger side and remove the front passenger wheel. Carefully unclip the mud flap from the inside of the wheel well and you'll see the alternator hanging right there. Look under/behind the alternator for the tensioner bolt and loosen it. Remove the belt from the alternator. Then disconnect both wires from the back of the alternator (careful not to break them). There are only two bolts holding the alternator. One is on the bottom and one is on the top. The top one is easier to reach from above and the bottom one is easier through the wheel well. It's helpful to have a helper as the alternator will just drop when you remove the mounting bolts. The alternator can be pulled out through the passenger wheel well and the new one can be put in in reverse of the above steps. It shouldn't take more than 1.5 hours if you don't know what you are doing. If you are somewhat capable then you can knock it out in an hour or less. The only belt you'll need to worry about tensioning is the alternator once you get the new one in place. Make sure you get it right. Too tight and you'll kill the bearings quickly, too loose and you'll burn up your belts, squeal, etc. You can get a little cheap belt tension gauge at NAPA that you just press onto the belt until is snaps. It will then tell you the tension within an acceptable margin of error. They sell for less than $20.00 or you can spring for the expensive one if you have loads of cash sitting around.
To me, draining the radiator and removing all the belts, etc. is a bit overkill for such a simple procedure.