Dont use boiling water on your skin-ever! That's really drying, and extremely cold water is shocking, so a tepid water temp (somewhere in the middle) is best.
I suggest just purchasing the Dermalogica PreCleanse if you want to try this method, to be mixing up different oils yourself at home, if you dont know what you are doing, you could end up really adding too much to your skin and could potentially damage it. Plus anyone with super sensitive skin or 'sensitized' skin that cant tolerate much, this probably wouldnt be for you. Sensitive skin can be further irritated by oils and 'natural' skincare which is usually chock-full of essential oils from plants and/or flowers.