I have to side with Shakhina but for different reasons.
I do not believe LV 5.1.1 supported control references.
Lacking control reference support there is no method available (to the best of my knowledge).
If it was 6.0 or better (just on upgrade from 5.1.1) this would have been a doable task.
I can not help you Jack Me.
For 6.0 and above.
All VI's in memory have methods that let you find references to all of the VI's controls. These can be manipulated in a variety of manners.
I had a customer that had developed a manual interface that let him poke and peak at an interface. He asked me if I could just use his code as is and poke all of the buttons for him. After an afternoon of work he had the crude functionality rquired to allow in to script feed his widget. The whole time his interface was up and running so he could watch what was going on. I slowed it down to let him convince himself it was working.
So with 6.0 and up, it can be done. Below 6.0, I think no.
There is another aproach that may be possible. I have to go on memory here, forgive me if I'm wrong.
It was possible in LV 5.1 to call VI's dynamically. Theoretically using LV 5.1.1 development environment, use an invoke node run method to launch the top level VI inside the exe. Once loaded, you list all VI's in memory to get a list of all of the sub-VI's used in the top level VI. From this point you could attempt to show the FP of any VI the original devloper included in the built exe.
If you really can not get a 6.0 or higher version or the source, you are at best facing a lot of work. At worst, an exercise in futility.
Trying to help,
Ben