Luarocks is a package management system for lua, for instance you can use luarocks to install luasql-postgres :luarocks install luasql-postgres
Then on your lua scripts you build on FreeSWITCH, you can use/include those libraries.
You only have to make sure to configure your lua.conf.xml and set module-directory to where the packages are installed on your distribution :
That's what I have at the moment with Ubuntu 12.04 :
<param name="module-directory" value="/usr/lib/x86_64-linux-gnu/?.so"/>
<param name="module-directory" value="/usr/lib/x86_64-linux-gnu/lua/5.1/?.so"/>
<param name="module-directory" value="/usr/lib/x86_64-linux-gnu/lua/5.1/luasql/?.so"/>
<param name="module-directory" value="/usr/lib/i386-linux-gnu/lua/5.1/?.so"/>
<param name="module-directory" value="/usr/local/lib/lua/5.1/?.so"/>