Saga gave us this:

Finally, if the target tries to escape aboard a starship, the hunter can
take a full-round action to make a DC 25 Use Computer check to detect and
analyze the departing ship's Cronau radiation signature. This signature lets
the hunter determine the point and angle of departure of a ship that has
entered hyperspace, and can give the hunter a good idea of the ship's likely
destination. For each hour that has passed since the ship made the jump to
lightspeed, the DC of the Use Computer check increases by 5. Scum and Villainy, page 87.

Decide for yourselves how to adapt (rather than convert) it. Note that DC 25 was a fairly hard difficulty.

3) As others mentioned, mapping out the trajectory. I haven';t written any rules on it since it hasn't come up yet, but I would basically allow the players to make an Astrogation roll to determine which planets are along the route (perhaps Average, but Difficult would work). Someone could also gauge the speed they are travelling at when hitting lightspeed to help determine the location of the final stop, but that is also pretty difficult.

It's possible, but in canon, there's been a large amount of guesswork involved to find the EXACT location of where the stop will be from trajectories.

Usually, they look at the planets along that line and make guesses where they would have gone based on the quarry. If they know the quarry well enough to know a few favorite hideaways, they can guess where they would need to stop to make a clean jump to that final location.

In the end, it's really up to how you want to handle it, but that's a few of the notes I have from my experiences. I hope they help!

Sublight speed would have nothing to do with how far you go in hyperspace. You don't have to have a "running start" to get further away.

Finding a trajectory and gaining any kind of concrete knowledge, especially along a main hyperspace route, would be next to useless too, as you have no idea how far along the route they go. If anything, I would say jumping to a remote world NOT on a hyperspace route would be somewhat better, but still very very hard to do, and that is taking a direct route there. Like mentioned before, if I was a pilot trying to hide from someone who might be trying to track my "last known trajectory", I would make a bunch of smaller jumps to confuse any pursuers before setting in for my final jump.

If a player was trying to track someone and hacked the opponent's navicomputer using their computer skills, I would allow them to gain the coordinates but only if the computer had received them already and was in the process of calculating the jump.

Just a point I'd like to make: in the X-Wing novels, they made comments about getting up to speed before jumping to hyperspace and needing that speed to arrive. Whether or not it is part of mainstay canon is up for debate, of course, but it is still a fact to consider.

As for your tactic, that is where that guesswork I mentioned comes into play. . .

Oh I havent read those books so I'd never heard it before. Thanks for citing the source, I'll have to check that out.

Not a problem. I may have misread it (last time I read one was back in November), but if memory serves correctly it came up during the Wraith Squadron arc.

It may have been just a requirement to have a certain speed in realspace that carries over into hyperspace, but then it makes me wonder why you need realspace speed if it doesn't impact distance and calculations. . .

I think that was actually in Rogue Squadron. There's a scene where Loor, an Imperial Intelligence agent, is trying to locate Rogue Squadron's base. First he plots the range of an X-Wing from the points where the squadron has been encountered to see where they overlap. There are several hunderd systems in the overlap zone though. Than he realizes that the first Imperial encounter with the reformed Rogues was when the Rogues were accidentally pulled out of hyperspace by an Imperial Interdictor on an anti smuggling mission so he plots the vector they were on when they dropped out of hyper and it points straight to their base. The Rogues had run into the Interdictor while on the last stage of a three jump evasive route from their training base to their first active duty base.

If expecting any sort of trouble or followers my group of players often do a small initial jump to nowhere, then stop and replots a course to where they actually want to go. They find it helps throw off pursuers.

Saga gave us this:

Finally, if the target tries to escape aboard a starship, the hunter can

take a full-round action to make a DC 25 Use Computer check to detect and

analyze the departing ship's Cronau radiation signature. This signature lets

the hunter determine the point and angle of departure of a ship that has

entered hyperspace, and can give the hunter a good idea of the ship's likely

destination. For each hour that has passed since the ship made the jump to

lightspeed, the DC of the Use Computer check increases by 5. Scum and Villainy, page 87.

Decide for yourselves how to adapt (rather than convert) it. Note that DC 25 was a fairly hard difficulty.

Had forgotten about that bit, mostly as it never came up in any of the games I ran or played in.

As for converting the difficulty, I'd put it at Formidable (5 purple). Reason for that is an average DC in Saga/d20 is a 10, which is 2 purple in this system. Each +5 to d20 difficulty is roughly equal to a one step increase in EotE difficulty ratings. For the part about an increase in difficulty based on time lapse, I'd likely put that as one setback die per hour, as a Formidable difficulty is pretty close to impossible for most characters anyway. I might also consider making it an impossible task (thus requiring the spending of a Destiny Point) of the fleeing ship was outside the pursuing ship's sensor range at the time it made the jump to lightspeed.

In regards to what skill to use, I'd say Astrogation would be the best fit, seeing as how Saga Edition had lumped plotting astrogation routes into the Use Computer skill.