You -could- keep the farseer, take prescience, guide, and psychic shriek, take the dual d-cannons on the wraithknight, then just plan on twin-linking the wraithknight and the group of scatbikes your farseer is sitting in every round. Due to the low number of shots, guide is amazing on a D-cannon wraithknight.
Also, obviously take invis if you get it instead of shriek, but it's not really that important on a wraithknight that's going to soak tons of firepower either way.
Personally, if I were going to do this though, I'd find points for a vaul's wrath battery with 3 vibro cannons, put your farseer in that unit, and use the second twin-link on them instead of the scatbikes. It makes for a sturdy T7 firebase for your HQ while averaging 3 S9 AP2 Pinning hits per turn.