Is it possible to "cheat" or adapt my gameplay and to activate a GOD mode in The Witcher?
Have you tried a trainer? These programs operate much like a "Game Genie" in that they can edit the values in memory in real-time and give you infinite health, potions, etc. You may have to try a few before you find one that has the features you want and works with the version of the game you have.
There are also save file editors, which will edit your save file so that you have near-infinite levels of gold, potions, health, etc.
If you want a more subtle help, you might try editing the game files, which will give you more talents per level than you normally get, which allows you to customize your experience to an extent.