Okay first off, you need to set up your alias, the pattern you want to enter is

^aim (\w+)$

then for the actual code

dir = matches[2]
send("aim "..target.." "..dir)

now you need to set yourself up a trigger off this line

You feel confident that your aim is accurate.

For the input you will need:

send("shoot "..target.." "..dir)

And that is all