Most textures in LOMAC use dds compression to reduce their memory footprint. However, this means that simply replacing the files will no longer work since they are bunched together in dds files. The only way I know to insert a modified texture into one of those is LOMAN.
That said, you can take the textures from the archive that you downloaded and place them manually in the 'TempTextures' (don't quote me on the name, but should be close enough
) folder in the LockOn/Bazar directory. The sim will look for textures named like the original ones in there and will use those instead if any exist. Expect to see a performance decrease (magnitude depends on how powerful your computer is) with high-resolution skins though, remember that no compression is applied to them if you do this.
The reason why most readme files are so brief is because LOMAN *is* the best way to install mods, once you have it working correctly
It's also somewhat unusual for it to cause any problems, so the best solution is probably to get LOMAN up and running.