I don't see any position options in the documentation for that function, but you could try one of these:
Since the method in question returns a Note object, you could use INote.SetTextPoint
So i would first create the balloon using the "InsertBOMBalloon2"" function, the to use the SetTextPoint, do i have to first retrieve the "created" point from the balloon that was created?
and the second question is the x y z coords, are they absolute? or offsets from the retrieved values?
This is something on one of my users wishlist's
Since the x, y, and z coords are absolute (from the bottom left corner of the sheet), you would not have to retrieve any existing location values to use this function, unless that is relevant to what you are trying to accomplish.
You need to get the underlying annotation from the note/balloon and then set the x y and z. I think the method is called SetPosition2. Your biggest problemo will be to convert the coordinates of the selected drawing entity from the model view space to the drawing space if you want to place a the balloon somewhere accurately.