Need Help w/ COLORMAP Lumps in SLADE 3.2.1

[Shark]

Greetings!

I'm working on a BOOM-compatible WAD that I want to have deep-liquid sectors in. However, I've hit a major roadblock when it comes to the COLORMAP part of the convincing-liquid effect.

I've been trying to see if I could make my own COLORMAP, but it appears that this is infinitely-more difficult than the simple flat/patch/sound effect/etc. that I've created so far. I've attempted to find guides online (and have also looked over Doomworld posts like this one), but I have had no luck in either creating my own COLORMAP (that doesn't change the entire palette of the WAD), or editing the colours of a pre-existing custom COLORMAP lump.

Here's what I need help with:

- If you can walk me through the process of editing a COLORMAP lump, or provide a more-helpful guide than what I have been able to find so far, that would be great.
- If you happen to already have a COLORMAP lump that changes the entire palette to green (deep nukage), or know of a WAD that has one, that would also be nice (though I'd like to know how to make it myself); so far, I already have two COLORMAP lumps that I have scavenged that are blue and red, but I haven't been able to find a green one.

[Worst]

If you download the BOOM editing utilities, the zip package contains a COLMAPS.WAD file that contains a few of colormaps, such as a red, blue, green, and gray colormaps. It also includes a command-line tool for generating simple colormaps.
 

[Shark]

34 minutes ago, Worst said:

If you download the BOOM editing utilities, the zip package contains a COLMAPS.WAD file that contains a few of colormaps, such as a red, blue, green, and gray colormaps. It also includes a command-line tool for generating simple colormaps.
 

A bloody legend, you are. Somehow, I totally missed that WAD file when I was perusing the BOOM Utilities folder. Exactly what I was looking for. Thanks!