Unlicensed Navigator
While in Imperial space closer to Holy Terra the laws surrounding the Navigators' Guild are more strictly enforced, out on the fringes of space, proper Navigators are uncommon at best.
Since on the Fringes, the need for space travel still exists, a class of instinctive, untrained, unlicensed Navigators has arisen. Their services come with no guarantee, and they are as likely to bury a ship in a daemonic hellhole as its appropriate destination, but nonetheless their services are in demand.
Though Licensed Navigators are forbidden from employing their abilities to any end but navigation, Unlicensed Navigators have been known to display warp-fed powers on occasion. Usually such a spectacle is followed by the Unlicensed Navigator being consumed bodily into a bleeding warp orifice.
FRP rules
In FRP, this would be run like the Hedge Wizard/Witch/Warlock career progression. Psychic powers would be available, but on a lesser scale than a real pysker. (Note on psykers: The use of psychic powers would be punishing and severe, to the extent that it wouldn't really be fun to use them.)
Cyberpunk rules
In Cyberpunk, it'd obviously be a different Role, with a special skill for Navigating.