Heh, it seems that people decided they'd rather not read through my lengthy post - I'd already mentioned I've Found Her.
I think the key to FTL travel via hyperspace is not that the speed of light is higher in hyperspace - after all, think how long it'd take you to accelerate to that speed - but that travelling a certain distance in hyperspace will take you a great deal further in normal space. Travel five miles in hyperspace, and then jump back to normal space, and you'll be tens of thousands of miles from where you started.
I think that the problem that these games - from RPGs to I've Found Her - come up against, as has been suggested above, is that hyperspace is not consistently described in the series, its mechanics adjusting to suit the storyline, a bit like the expanding ships from the series.
Another theory, perhaps - large warships have sufficient inertia to avoid being swept off course by hyperspace currents (unfortunately, 'gravitational tides' are mentioned in various places, which of course impart the same acceleration no matter your mass), and so can project their courses with sufficient accuracy to depart from the tight-beam transmissions between gates. Also, if the direction of the tidal forces is essentially random, or at least uniformly distributed, then they will tend to even out over time, so provided you move with sufficient speed that a given current only moves you slightly off course before you're past it, you can go in a straight line largely without worry - and if you can detect the forces acting on you, you can correct for them.