Predefine Input Path Parameter

I hope this is the correct forum...

I have a Python script that I'm running as a tool within a toolbox. As a parameter, I require the user to pick a .sde file from the file system. Is there a way for me to specify the folder that the user browses to look in?

For example, if I have a folder with .sde files located at c:\SDE, when the user goes to select the .sde file, I want that folder to be predefined so it appears in the file browser. Is it possible to define that file path? I tried setting it as the "default" setting, but that only defines the parameter, it doesn't open that folder path within the browser.

Thanks,
Andrew