I guess I found (most of) the solution. (I did not find the way to get the nemotic though)
simply find on github litecoin-project / liteaddress. org
download the code as zip (green button), turn off internet (per security), click on the index.htm then follow the intruction.
ps for litecointalk people: you should put this information in your home page (well, if you want people to use your crypto…). Once again it feels like the crypto people work had to avoid having too many people buying/using their crypto (exept BTC). Like many (most?) people, I was just looking for the most feature : how to get a private key + adress (without downloading GB of stuff, and without depending on specific app, I just want to get my private key and keep it where I want)
You could install a wallet / key manager ( like coinomi ). For besr security, you can run on a cold ( no internet ) tablet or old phone. That will generate and manage public/private keys. I use it as a hot wallet on my phone and love it.
To create a paper wallet ( sounds like what you’re doing ) you could generate a public / private key pair with a web key generator ( installed to an offline PC for better security ) then print to a USB printer. There are lots of options for paper wallet generators if you just Google ‘Litecoin paper wallet’
Both methods get you pub/priv key pairs.
If you’re feeling ambitious, you could make a a random private key yourself by flipping a coin 256 times and convert that to a compressed public key in with your favorite coding language
I hope this helps!