It won't reload automatically, you'll have to use the reloadimages console command whenever you want to see changes. Bind it to a key and it'll be even better!
Doom 3 has those various reloadX commands, use listcmds or type reload and press tab. Though Pogonip's post sounds like it'll detect the changes and reload the texture automatically. However, does the Doom3 display have much control over specular maps and such? Um, what control do you mean? All it does is take your spec…