For me the easiest way to do this was to go to the
Serpentis system and just travel from planet to planet, disabling Va'ruun ships, boarding them and then taking them. There's a high chance to spawn at least one ship every time you travel, they do often take between 10-20 seconds to spawn after you arrive so wait before you fly to another planet.
The system is Level 55 so make sure you're a fairly high level before attempting this, I used the Targeting Control Systems perk to target their engines and disable them, but you might find using
EM weaponry easier if you don't have any skill points available.
After you sit in the Pilot Seat, press
, go to the Ship option on the bottom left and then press
again to make the new ship your home ship. After that, hold
so you exit the menu, this will automatically undock you from your main ship. Then quickly use
to target your old ship before it flies away, hold
to dock and then make your way back to the Pilot Seat and make it your home ship again. Exit and then the ship you just took over will fly away, leaving you to carry on to the next planet.