If anyone runs into problems with it not properly launching, try downloading and installing the latest libraries from http://lwjgl.org/download.php . Solves it for me with the latest launcher.
To install, simply delete the lwjgl.jar, lwjgl_util.jar and the jinput.jar ONLY, and replace with the corresponding jars from unzipped folder.
Then, inside the unzipped library, go to the natives folder, and copy the files from the folder corresponding to your operating system (Most likely Mac) into the natives folder in your .techniclauncher/<modpack name here>/bin/natives folder.
If at any time you feel you've done something wrong on the install, simply start the techniclauncher, go to options, and hit clear cache. This will restore the library and the natives from the servers.
Hope this solves some peoples problems, it always works for me :)