Well, I believe the Hitec servos come with the black blank disks which you could drill using the SWM setup tool I've seen sold at various places. Or you could use the red cross style horn and just place the ball links in the proper holes. I belive the red horns have the distance from center marked right on the face of the horn next the the holes. I used JR8311 servos with the large diameter disk style horns.

Now the question is, do you have the HWM or the SWM type linkage setup.