Tutorial:
After installing the Required Software, open the DOOM.WAD in XWE.
From here you want to goto the top and select ENTRY then LOAD (raw data) as seen in Example 1 to the right.
After you have clicked on this, a folder will open and as for you to select the file you want to Load, which in this case will be a file that I have titled DEHACKED.DEH as seen in Example 2.
Once you have selected and loaded the file it should appear somewhere in the upper section of the list as seen in Example 3. If you do not see the file, you should be able to type it in the box above the press enter to have XWE find it for you.
Once you have found the file you loaded, you'll need to make sure it is titled: "DEHACKED", but without the "'s. If it is not named as such, then rename it now or it will not work!!!
At this point you can close XWE and it will auto save the modified DOOM.WAD, but if you try to load DSDOOM off it, you will end up at a black screen. I could go into the reasons for this, but I'm not going to, I'm only going to explain what happened and how to fix it.
If you open up XVI32 then load up your altered DOOM.WAD then look at the right hand screen. You'll see that the first thing it says is PWAD. What it needs to say is IWAD, so you merely need to put your mouse pointer on the "P" and change it to a capital "I" (as in Indian or Independant) as shown in Example 4.
Now all you have to do is save, copy the DOOM.WAD file over to your DS, and you should be good to go with your new DeHackEd enhancements.