Rick already described a way to accomplish the "functional" result you wanted, but not in the technical way you asked.
Did something similar few decades ago on a really large app to add special logging for a couple of installs showing weird behaviour. Approach per se works, but is a backdoor baked in your exe.

Few years after fix independent security audit "found" that (comment was something like "white hat backoor") and I was very glad to be able to forward my email correspondence with warning description and 2 queries right before release update builds to delete, deactivate via outcommenting or leaving as is.

As security gains importance, make certain you don't need to rely on others to remember your warnings ;-)

>I have an app that has a .prg like "start_main.prg" set as the startup program in the project.
>
>I'd like to know if there is a way to change that via the command line instead of using the project manager to do it...so if I wanted to change the startup program to "start_main_test.prg" is there a way to do that from command window?
>
>Thanks!