I have done the best I can with PermissionsEx and ModifyWorld.
I have checked it with the YAML checker, that was included in the forum post on bukkit, and got no errors.
I would like, howsoever, for anyone to check if I made no mistakes with making the Tekkit items forbidden, if you can.
I have uploaded the permissions.yml here:
http://www.mediafire.com/?f69swwop567qmnn