Usually if I don't know the parameters of a function, what I do is I go into SparkIV and check out .sco files in script.img to seehow Rockstar used the function. You have to think of a mission where they might have used something like this and then go check it out.
In ray3.sco, you will see this line:
ADD_EXPLOSION(-267.1f, 751.29f, 11.63f, 0, 0.5f, 0, 1, 0.0f);
Now I have no idea what those last five values are, but you could duplicate them and put your own coordinates for the first three, and see what happens.