so far, it seems that CoD will accept jpg and tga texture formats. I found a number of them in the original pk3 files.

The other format is dds. Here are some downloads for this:

photoshop dds windows driver
Photoshop dds plugin
dds thumbnail viewer

This is a DXTC texture compression plugin for Adobe Photoshop that allows you to open and save .dds files in RGB format. The plugin reads and writes .dds files compressed or uncompressed.

Requirements: You will need to place the plug-in (dds.8bi) in C:\Program Files\Adobe\photoshop 7.0\plug-ins\file formats and this required dll (msvcr71.dll) in your Windows\System folder.

I was able to open and save dds files with photoshop with the above downloads.

dds files differ from other images because they carry tecture-like characteristics and information including mip maps. When saving from photoshop, a popup box with come up allowing you to set the properties and autogenerate the mip maps... quite nicely too.

I haven't tried putting all of this new info into a custom map yet, but now it would seem that I have all the ingredients.

That plugin will also work for Paintshop Pro...
1. Place the dll file in the windows/system folder
2. Create a plugins folder in the Paint Shop Pro folder
3. Place the dds.8bi in the plugins folder you created.

Yup, I had to use these plugins for Elite Force 2 editing.