How can I get info about context of signal of my model when code generating

I have been trying(ML2013b) to find a way of defining a signal object i.e. F_M_Xxx in my model and then I would expect that when signal is used to write something into it I would get a code RAISE_FAULT(&F_M_Xxx) whilst when the same signal is read then I would get GET_FAULT_STATUS(&F_M_Xxx). The scenario here can be when you have a block and it writes to Outport so my signal is on the line to that Outport, then at the same time Switch block takes it as an input.

I have to say that I explored Custom Storage Classes and came across GetSet custom class which seemed perfect but the restrictions of GetSet make it not possible for me to use it. So I just wonder if with those CSC I could develop a new class and then in its TLC somehow discover what context that variable/signal is used for read or for write and then customize the code in TLC script?

I tried with LibCustomStorageRecordIsBlockOutput but it is not what I want but well, close:

%case "contents"
        %assign id = LibGetRecordIdentifier(record)
        %assign isBlockOutput = LibCustomStorageRecordIsBlockOutput(record)

          %if isBlockOutput
            %assign rtn = "RAISE_FAULT(..)"
          %else
            %assign rtn = "GET_FAULT_STATUS(..)"
          %endif

          %return rtn
          %break