You first need to extract raw textures from their archives. You can do so with UltiNaruto's PitfallArcTool.
Converted textures will be stored as files of the chosen format in the output directory.
Usage:
TexConvert [options]
Options:
--input <input> The path to a texture or directory containing texture files
--output <output> The output directory [default: current directory]
--format The output image format [default: Png] <Bmp|Dds|Gif|Jpeg|Jpg|Pbm|Png|Tga|Tiff|Webp>
--vflip Flips the image for human consumption [default: True]
--combine-textures Combines natively-split textures into single image [default: True]
--version Show version information
-?, -h, --help Show help and usage information
WIP