Be more specific! You mean objectives of HUD messages or nav points?

Create a notepad file called hud messages.hmt
in that put stuff like this
obj1=>> appears ingame
obj2=>> yup

obj1 and 2 are what you refer to it in the script; >> app/yup is what appears ingame.
Save the file and compile it in tool. (File should be in data/levels/whatever)
tool hud-messages levels/whatever nameofscenariofile

once it compiles it should already be associated with the scenario
now just script it in
(script startup test
(show_hud_help_text true)
(enable_hud_help_flash true )
(hud_set_help_text obj1)
(hud_set_objective_text obj1)
(sleep 120)
(show_hud_help_text false)
(enable_hud_help_flash false )
)

Maybe you should start with something more simple like scripting