Theoretically, there's a way to "sort-of" trick the system, but the chances of it working plummet when the number of people queuing increases. It also requires that you have a steady stream of people who don't want the "bonus" loot (let's call them 'dummies').
Dummies queue for the desired heroic...say Oculus.
Rest of the group queues for random.
System tries to put a group together based on what roles are available (hence the more people doing this mean less success).
System sees dummies looking for Oculus, and needs to fill their group.
Random group gets paired with dummies.
In reality it only has a tiny chance of working, given the size of the pool of players...but that's the theory.
TL
R? The more people specifically queuing for Oculus, the better the chance people queuing for random dungeons will get it.