Uhh what do you want then? There is a gregtech.lang file inside your Minecraft Folder, just set B:UseThisFileAsLanguageFile=false to B:UseThisFileAsLanguageFile=true and you are good to go when it comes to working on your Localization.
Just post the resulting File in the Localization Category. ^^
As for your Lets Play Guide, depending on Language you should post it in the International Category or in the GregTech 6 Category. 