You will have to keep in mind where your space is on the Edison and put as much in the partitions that have your free space.
In the default image, issuing a df command will give you your partitions, you will note that /home has your free space.
In that light, I would move your lua-5.2.3 to /home/lua-5.2.3 and then use a soft link (adjusted from above)
mv /lua-5.2.3 /home
ln -s /home/lua-5.2.3/src/lua /usr/bin/lua
chmod 755 /usr/bin/lua
this way the least amount of space used from /usr/bin is used by the link (which is the root / partition)