Note: If you ruin your jeans, my bad. This is an Instructable, after all.
Step 1: Ingredients.
I went with RIT dye. because it's the most common product. Once you decide to do this, keep in mind, it's messy as all get out. I would recommend only using stainless steel items in this process, unless of course you want to piss of your wife.
Of course, you'll also need some faded jeans. For practice, of course, you may want to try it on some you don't care about.
Step 2: Mix the Dye.
You want 2-3 gallons of hot water in your mixing container, Add your container of blue dye and you container of black dye. Additionally, add 3 Tbsp. of salt to the mix. Stir until everything is dissolved.
Step 3: Prep the Clothe.
At this point, you want to prep your jeans. Basically, if you have tags or items on the jeans that you don't want dyed, you should remove them.
note: it's recommended to turn the jeans inside out at this point. It seems to allow for better saturation.
After you have done that, moisten the fabric by running them under warm water. Squeeze out the excess water and place them in the dye bath.
Step 4: Saturate and Wash.
Note: Warm water cycle, no detergent.
The key to this process is to experiment with the amount of time and amount of dye.
Step 5: The Results.
note; If you mess up your pants, I'm sorry. I've wanted to try this for awhile and I hope you are happy as I am with the results.