If you've got departure, destination, and thrust that narrows it down considerably. That would be enough to jump to the vicinity. And you're likely to have those if you know the one shipment you're going after, say the one that's Radioactives rather than Common Ores. Which you're likely to have, otherwise it's chicken thieving scale piracy rather than train robbery.
Without jump inbound, you either go for stealth, or just gray man camouflage as regular traffic. Or get on board as the guards or crew. Then ideally you jump away, or else try to pull it off without anyone knowing until it docks, cross in suits on sleds so it's not immediately obvious which ship it was.
A considerable list of challenges, I haven't even listed everything, but that's what makes it a train robbery or heist rather than a single combat encounter.
OR, be hired as the guards, and let the NPC pirates figure it all out.