It seems that "npm pg" (https://github.com/brianc/node-postgres) is the prefered module to interact with a postgres database from a node.js script.
nevertheless this module does not support binary large objects in the form of postgres "Large Objects". It only support the bytea format.
Is there a module that I am missing that has lo support ?
You would probably have to write your own support. Note that libpq basically just calls functions over an SQL interface. See http://www.postgresql.org/docs/9.1/static/lo-funcs.html for more documentation.
If you need to, you can refer back to the libpq client interface docs and then use \df to see how to invoke these in PostgreSQL.