I am developing a C# application to automate the running of a legacy VBScript(vbs) file which calls several VB6 .exe files. The .exe files have message box pop-ups that I need t
You might find AutoIt helpful.
AutoIt v3 is a freeware BASIC-like scripting language designed for automating the Windows GUI and general scripting. It uses a combination of simulated keystrokes, mouse movement and window/control manipulation in order to automate tasks in a way not possible or reliable with other languages (e.g. VBScript and SendKeys).
You can develop something using only the AutoIt programming language, or you can drive it from your own applications. My team's using this, with good success.