I'm guessing it's not implemented yet, but this is my work around for the moment.
Select your waypoint
Designate your waypoint as target "WPDSG" (so you can see the diamond on the hud)
With your TGP boresighted, move your velocity vector over the diamond (Cage/uncage button to boresight TGP)
Press TDC depress so your TGP look in that general area