After building from Quorum source, I can see Swarm as on the binaries. How can one get Swarm to work alongside Quorum?
Quorum is first an Ethereum client.
It's based on Geth, the Go client implementation of Ethereum but adds some privacy features such as private transactions.
Quorum is then capable to use smart contracts as the main Ethereum protocol and so also use Swarm as decentralized storage. The use of Swarm is then the same as for the main Ethereum client. See What is Swarm and what is it used for? and http://swarm-guide.readthedocs.io/en/latest/introduction.html for more information about Swarm.