Pop-Up Picker

[datawiz]

I am working through Scott Love's article in FileMaker Advisor on making Pop-Up Pickers (August 2006) and wanted to modify his technique, but wasn't sure how. Essentially his technique is that the user clicks a button that calls a script to open the pop-up window. When the user clicks on the name of a person in that window, a parameter gets passed up indicating which field is wanted - in his example it is the primary key of that person.

I would like for that pop-up window to return the results of different fields (possibly the primary key like Scott had, or possibly a foreign key depending on what I need at the moment), and I would like for the name of the field needed to be passed up as a parameter from the original button. But I'm not sure how to specify a "needed field" earlier in the process.