You go into setup and arena settings and under Flight Mode Flags you enagle the Lead Computed Gunsight, I think I left out one step in the location processs though.
Hit 'Ctrl-tab' to enable Friendly lock and at that point 'tab' or 'Shft-tab' will highlight the target. 'Tab' to cycle through all targets in your view and 'Shft-tab' to highlight the centermost one. It brings up small green +'s that show the exact lead needed to hit the target. You have one + for primary and one for your secondary weapon.