Make Tac Missiles not home in on targets?

That would only affect manual firing against the ground. Missiles would still have seeking behavior if given a target.

No I mean make the missile command a groundfire one.

I've not had a play with staging, but could you not set up your own staged missile which is guided at its terminal aim stage to point to target, and then become an unguided ballistic (with the ballistic value being higher like the sheller perhaps?) or direct-fire projectile? Would still look like a tactical missile but wouldn't turn at the last stage where it traverses to target. Either that or I am just totally misunderstanding the staging system.

Edit: Had a look - should be totally possible. Not quite sure what "stage_change_range" means though - only progresses to the next stage if it's at a certain range? Shrug. Might test it out later in the week. I suppose you'd need 3 stages I think, a stage_turn_rate 0 lasting for the duration of the vertical climb, a stage to turn to face target, and a stage to fly to target with no turning again.