I'll try and make this as painless as possible, if I miss anything, please leave a comment and I'll add it on.

Parts, Tools & Screws Needed for Xbox 360 X Clamp Fix

1. Roll of Paper Towels

2. Box of Q-tips

3. Package of Tooth Picks

4. Cotton Swabs

5. Thermal Compound Paste

6. Bottle of Rubbing Alcohol

7. Flat Head Screwdriver

8. Regular Screwdriver

9 . 13/64 Drill Bit (some people prefer to screw the heat sink to the chassis, but not needed)

10. Cordless Drill or Regular Drill

11. T10 Screwdriver

12. T8 Screwdriver

13. Scotch Tap / Masking Tape

Update 9/25
Here are the official home depot part numbers and screws!
Qty - 8 Machine Screw Pan - Phillips 5 x 10mm (DR# - 313) UPC - 030699 801282
Qty - 16 Flat Washer Nylon #10 (DR# - 610) UPC - 030699 869381
Qty - 16 Flat Washer Steel / ZINC Plated 5mm (DR# - 606) UPC - 030699 363087

Alright, the Scotch tap is there to help you when your putting the screws back though the heatsink, so you can get the nuts on the backside of them, without doing it one at a time.

You can get the thermal paste at any computer store and you obviously know where to get the rest of the stuff.

As far as the drilling goes, your don't necessarily need to drill wholes, but some people prefer it, to tighten the heatsink up that much more by connecting it to the actual shell of the console.

So that's it, like I said, if I'm missing anything, let me know, if you have any question please leave a comment.

Also, keep in mind, that it's strongly recommended you don't try the Xclamp fix by yourself, you should really get the Xbox 360 Red Light Fix guide to walk you through everything, plus they have an awesome troubleshooting section that lets you pin point the exact problem and what you need to do to fix it, sometimes you don't even need to take your console apart and I should also let you know that, the X clamp fix is only one alternative out of many options.

Here's the Link, Xbox 360 Red Light Fix

Be Careful