If aliens could make it here from lightyears away, they would need access to physics far far beyond ours. But if they did have it, it could look something like this.
As a proponent of rolled up universes, I believe that all possible sets of laws of physics exist as seedling universes, as small as a particle, just waiting for the right conditions to exist for them to expand.
So an alien builds a spaceship, perhaps out of steel and other vacuum resistant materials. But what the spaceship needs is a means to expand a superluminal field around it.
The cosmological constant was a term added to the Einstein equations to explain why the universe is accelerating in its expansion. It is something that works opposite to gravity, it causes space to expand.
An alien hyperdrive system will have generators that increase the cosmological constant of a superluminal field around the craft. No doubt the field will decay quickly, requiring the the superluminal field generator to always be working. If it doesn't work, your ship will not travel superluminally.