Well there are two things you can do:
First, if you can get to the block diagram, you can probe any wire while the code is running.
Second, you can create a VI that does nothing but display the data that you want to see. To view the monitor panel use VI server calls to open the monitor VI's front panel.
One thing to remember is that no monitor function is ever totally "transparent". For example, the update time for an indicator can, under certain circumstances, adversely effect the execution time of a VI.
Mike...