Pass a Property to a Search Grid

For our projects we may have a large number of documents and we're considering different ways to handle this other than trying to recreate some sort of "folder" ItemType to assign them to.

One concept we have is the idea of either having buttons or some sort of query that would run and display the Search Grid, but with various pre-filled parameters and automatically run the search.

Any example would be the following:

- Document ItemType has a property of _project which is associated to the ItemType Project

- Document ItemType also has properties like _function or _discipline which could be Engineering or otherwise

The button would launch the Search Grid, pre-fill the Project with the Project filled out in the grid and pre-fill the _function or _discipline as needed.

I've added a button to the toolbar and been able to assign a method to launch the Document Search grid via http://ourserver/innovatorserver/client/?StartItem=Document, but I don't know how I could pre-fill the fields and auto-execute the search.

Any ideas on this?  Thanks in advance!