The FTB support forums are mostly for FTB support. Tinkerers construct and Gregtech are part of FTB, but the launcher doesn't support 1.6
You should ask in the Modding section of Minecraft Forums, or their respective threads(
here and
here);
Considering you have a vanilla 1.6.4 Minecraft, download forge installer from
files.minecraftforge.net, then start it. Then just download the Tinkerer's Construct .jar, the IndustrialCraft2 .jar and the Gregtech .jar and put them in the /mods/ folder.
