I've resisted this for some reason all these years, but finally encountered a situation that requires it:
$ love ./
This runs the app, but with an identity of 'lovegame'. So all new save dir, etc.
T42Y5MLOV7WMURTBEZTUVMYEVG72UMN6BPG2QHOYW7G2CC75ZNGQC
function love.conf(t)
t.identity = 'lines'
end