How to control the default folder for the IDEAScript's CommonDialogs?

Hello All
 
Thanks Brian for this helpful site, it has really helped me a lot of times!
 
I would like to ask you the following:   I have a set of scripts that I run monthly in diferent projects, of course I do not copy the scripts to every project, but I run them from a specific folder. 
In the process I execute I have to select several templates which are stored with the scripts, not in the projects.  To select the templates I use "Client.CommonDialogs" and  "obj.FileOpen(...)", but as I run those scripts on each project, everytime I use them they point to the previous project.
I solved my problem partialy, by using the first and second arguments of obj.FileOpen(), in the first I put as extension "*" and in the second argument (which belongs to the file name) I include the path and as file name another "*", this way it reads the path I want to use.
I wonder how could I change the folder, by Script, in order to control which folder I can go to without using those parameters that I mentioned?
 
Thank you in advance!