I suspect you really want to be using schCreateSymbolPin - this creates a pin using a cellView as a master - which is what the create pin command in the symbol editor does.
In the CIW, if you type:
you'll see which cellViews are used for which master. For example, you can see that basic/actHiInp/symbol is used for actHi input.
So you could do:
; coord is where you want to place the pin. cvId is the database Id of the symbol
pinMaster=dbOpenCellViewByType("basic" "actHiInp" "symbol")
Only you can know where on the symbol you wish to place the symbol. In the symbol editor, if you do Options->Display and turn on "Coordinates in status banner" so you can see where is a relevant location.
The same would be true if using schDrawSymbolPin - this is just expecting a list of coordinates for the red blob which is the pin. You need to determine where you want them to be - I can't work that out for you.
As for replacing an existing pin, easiest to delete it and re-add it, I guess:
; termName is the terminal you want to delete, cvId the cellView
Or something like that...