There is no forge file in the 1.7.2(unstable pack) mod folder. I tried to download the installer but there is no bin folder in the ftb 1.7.2 folder.
Sorry @
Tomnickles. I was in major derp mode... So much so that I did not realise that @
Yusunoha's method is for the mods themselves and not for the forge update itself. Somebody shoot me!
Okay, this is how you update forge....
Download the forge client for the MC version that you need or in some case, the mod you want to use has recommended. Some mods specifically mention 1024 and above, 1032 and above, etc.
Then run the exe, or if using jar, execute it with the java executable. Then forge application will automagically detect your minecraft profile dir and depending on the version, select the version that it will "update". Just accept the defaults.
You will be informed that the new forge version enabled minecraft instance was written to dir named "1.7.2-forge.xx.0.xx.xxxx".
Launch your MC launcher, and start the profile with the last 4 digits that resemble the forge version you updated... You will get the modded MC launcer window with the 3 mods added 3 mods active message on the start screen... It means all is well in the land of Minecraftia.
Makes sense?
So, once again, sorry man..... What was I thinking anyway when I read the OP in the first place!
[makes favourite noise "BLARGWWAARGGFFLLL" and bows out]
EDIT: Make it easy on yourself... Use one of the launchers in the market Hint.. Hint...