I tried this just a few minutes ago, and it went smoothly until it came time to repackage the Forgified MC_server.jar. I can't seem to compress the mctmp back into the MC_server.jar.
I tried a few times now with some mixed results, once or twice it would return with the "Invalid or Corrupt" line from before. However it did come back with
so I guess that is a small step forward, right?