So previously changing the cfg.lua was enough to make everything work. This time I had to open the Makefile and find all the locations where the "lua" bin was mentioned and change it to "sblua" and do the same in the configure file.
I made those changes then passed the sblua include file and /opt/crank/bin where sblua was located and boom, luarocks using a custom interpreter name.
Next up was installing some luarocks.
I installed luasockets, luasec, inspect, and lua-cjson off the bat.
In order to install luasec I needed to run:
sudo apt-get install libssl-dev