Create application form trigger??

Hello,

We want to create our custom button on on a certain predefined by some of our third party vendors Application form. It can easily be done with code like bellow:

      hiAddField(certainForm list(our_custom_button 200:600 200:25 140))

But the problem is that the form should be opened in order button to be added. So it will be best if some trigger could be set whenever the form is opened our button looading procedure to be executed.

Do you know if such kind of triggers exist?

Thanks,

tyanata