have a friend on the server build a nuke flash chamber to kill you once you log in. even thought the scree is black and or have turned white, it will still say on their screen for a moment that you have logged in. once they have killed you. log in. one your screen you should be able to see yourself dead on the screen. hit re-spwan. if you can't log out and log back in and do not exit the window or you will not be able to hit the re-spwan button. now hit re-spwan and wa la! tekkit works again.
~ Courtesy of (canwebefriends)