Make sure lua package is not installed. Right now, we conflict with lua package, and our CMake package generation does not handle conflictual packages.
Then simply do
sudo dpkg -i Torch5-XXX.deb
You might have to install dependencies. If you have a old distribution, it will complain not finding QT 4.4. You can follow our instructions to create these packages.
You can then run Lua with
qlua (handles graphics an IDE) or
lua (no graphics).