Thanks for the suggestion, physlock doesn't look too bad!

It locks fine from the console as well as from X running on Grml, I just noticed
exit code 1 saying "physlock: error: could not deallocate console # 8: Device or
resource busy" when returning from the lock when running in X, but that should
be something manageable and the lock itself seems to work just fine.

The software should be easy to package (simple "make && make install" does the
job), anyone volunteering to package physlock, Alexander or Evgeni? :)