change the folder name of common a dialog

[pokpoki]

Hi,
i want to change the folder name of a common dialog control
that belongs to other application.

for example:
i'm getting a save common dialog from one application with
default directory ("C:\temp" , for example) and i want
to change that directory (to "D:\Program files" for example) with api code (not manualy).

How should i do it ?

thanx alot,
pokpoki