I used the "deform sprite" material keyword to make them always look at the player, it worked but it automatically forced the material to no shadows and no light interaction, because i wanted the "always look at" functionality but also be able to use the material with normal maps and stuff, i removed that keyword and code my own system, only using doom script.
In the end i used a no light interaction material for the grass and no shadows but it was a nice lesson on idtech 4 scripting.
This is the small code doing the magic, perhaps there's a better way but this works and for now that is what matters.
But anyone is free to come with a better way.
player_angles = lod_player.getViewAngles();
player_angles_x = 0;
player_angles_z = 0;
player_angles_y = player_angles_y + 90;
lod1.setAngles( player_angles );