First, you need to download a game editor. You can find one here. Scroll down to the Witcher section. Be sure to pick the correct editor - there is one for the original game and one for the enhanced game. Download it, unzip it, and place it in a directory.
Next, read the "Read Me" text. You will find that you will need to download java 1.6 runtime if you don't have it on your computer. I simply googled it, downloaded it, and installed it.
Next, you need to follow the directions on the Read Me to set up a shortcut to the jar file. There is a shortcut included but it looks for a set up like "Disk letter\Game\Witcher Enhanced." For example, mine is C:\Game\Witcher Enhanced so it worked. If you don't have it set up that way, and have way more experience with computer language than I do, you can follow the directions to make it work from any directory. Good luck with that.
I will note that I simply clicked the shortcut and somehow the files got loaded into the Witcher Enhanced directory. I don't have an explanation for that.
Also note that your saved games should be in the default location, which is in the My Document directory. If not, you can read the complicated code to redirect the editor to find them. Also, I highly recommend saving the save game you are going to alter to another directory or safe place. The editor does not save your original, so you would be screwed if it is corrupted.
Once you get the editor to work, java will load up a blank screen. Choose File -> Open. Load up a saved game. There are tabs across the top. Look for the second from the right that says "Inventory." Click on that. In the right pane there are a number of directory choices - choose "Quest." Scroll down the alphabetical list of items until you find "Holy Flame" (that in itself took 45 minutes because I was looking for "Candles" and could not find them). Underneath the pane is a button that says "Add Item." Add 5 of them. Choose File -> Save. Close the program. Enjoy.