To be honest, 35% H2O2 isn't required; you can get 20% strength from 'Sally' and that will be sufficient for most people and will offer more control of the process. I certainly won't be selling any kits as there is too much liability attached for my liking.
Here's the formula, you lazy git, LOL
1 pint Hydrogen Peroxide, at least 20% strength
1 teaspoonful xanthan gum (health food shops or Ebay)
1/2 teaspoonful 'Vanish Oxy Action Plus' (any 'Oxy' laundry booster will do)
1 teaspoonful glycerine
Gloves and Goggles (Safety First!)
1 UV lamp
Liquidiser or hand blender
Chuck all ingredients except the Oxy into a container and mix until a smooth thick gel is formed. Just before you use it, add the Oxy in by stirring and then brush the mix onto the item to be treated. Stick it under the UV lamp and check regularly until the yellowing has gone.
Oh, and please take photos so we can see the results...