I'm reposting this from the questions thread here
Every body has a blueprint to which the cells conform. It is called the etheric body. In alchemy, it is the mercury (physical body is salt). You can think of it as a hologram that is like your physical body but without the random bits of damage and stuff. If you made a hole in your etheric body, the cells would not heal in that spot, and would dissolve. If you make a hole in your physical body but not your etheric body, that space is filled in with blood and so on and your body repairs itself as best as it can as it strives to retake the shape of your etheric body.
Every etheric body in turn conforms to an idea/archetype/essence aka the astral body (sulphur in alchemy). This is your "energetic signature".
• Salt denotes the physical component, the seat, base, matrix, anchor, or ark of the nonphysical aspects.
• Mercury is the etheric component and represents the dynamic, vital, transmutative, vivifying energy present within the substance.
• Sulphur denotes the archetypal identity or pure vibrational essence, analogous to the human astral body and spirit because it contains the “Idea” unique to that substance.
You will want to start by experimenting on a different body than your own (maybe a plant or some animal or something) but you can change around these bodies and reprogram them.
This is the key to changing your own body ultimately. However you're also going to need much more etheric energy than you are configured with by default to power the transformation quickly… otherwise it might be very slow (on the order of, however long it takes for every cell in your body to be replaced, and that would only even happen if you had double the default energy… you're probably going to want far more than double).
You don't need a demon or other entity to change your body just your imagination and a lot of power. However I would still obtain the assistance of other entities whether they be ones you created yourself or ones you met via channeling or whatever in the operation, especially as you might pass out during part of the process of transformation, as has reportedly happened to some other people who have done/attempted it.
I would suggest that for today you get yourself a glass of water and you start creating thoughtforms of roses, smelling the roses, and seeing them in perfect detail. Let the water droplets on your roses you've thoughtformed drip into the glass of water and infuse it with its scent. Then drink the water to test it tastes like rosewater, then bottle it up in a glass container with a seal, and drink some of it again another day to test it. When you are able to do this meditation and create rosewater that retains its rose scent and taste for an indefinite period of time, the next step is to find someone else to taste your water, and if they notice it smells and taste like roses you have completed this exercise. This simple exercise will develop many faculties simultaneously which will prepare you for the transformation of bodies. When you are more adept and understand the principles well and have applied it already to many things you can then apply it to your own body. In this case, you would aim to make your sweat smell like roses. Once you're able to walk into pretty much any room and anyone notices you smell like roses you have succeeded. After that you will want to experiment with alchemically modifying and transferring all sorts of different properties to bodies… you might even change lead to gold if you want. Eventually you'll want to replace your own DNA with that of a female and you'll want to make sure you have enough power to do it completely all at once for otherwise an awkward chimera condition could take hold in which some of your cells are that of a woman and others are that of a man.
A tulpa or other being can help assist you in the whole process. Make sure if you create a tulpa you do so out of pure intentions and not just to satisfy your lust… you want to create a servant that will be very friendly and helpful and keep you on track not one that will lead you away from your main objective.