To be honest, I know how to extract, convert, apply/create bump maps and surface decals, but not much else.
I’m sticking to editing of the .vmt as to edit the textures themselves, I’d have to even more editing which would mean converting them back to .jpgs, whcih will take frickin’ ages and I was hoping to releases them sometime tonight.
There are 2 options that could convert back and forth between VTF and Targa/ JPEG if you wanted to just get it back into photoshop easily. One solution is based around a plugin for vtf’s for photoshop, I don’t know if there are paint.net or gimp plugins for vtfs that work in the same way. While the other solution converts the vtf back into a image format that you can then edit in your photo editor of choice.
The batch conversion method uses VTFedit (http://nemesis.thewavelength.net/index.php?p=40) which is a stand alone program, with more advanced features then the photoshop plugin I am going to describe below. It can batch convert folders of vtf to image format of choice (batch converter’s options output jpeg, targa , .png or .bmp). While also can convert the image format it takes (JPEG, Targa, .png, .bmp, .dds, etc) into the vtf. So basically you could convert all images, fix them up in photoshop or editor of choice, then batch convert them back to vtf.
Presuming you are using photoshop as the editor of choice, there is a plugin wrote by the person who coded the vtfedit application, its dll being wrote by another programmer, same dll being used for vtfedit.
The plugin allows photoshop to open up VTFs directly, rather then having to go through the process of conversion. This way you could do what you wanted, then re-save the vtf again avoiding the issue of batch converting all of the files you have. The options for saving the vtf are less advanced then vtfedit.