Changing location for Directory of Documents

Hi,

Can anyone guide me how i will be able to change default location picked for Directory of Documents.

SAP GUI>Options>Local Data>File Lifetime(Navigation to view Directory of Documents)

i want it to point to a different location. After a lot of reading i found out that this can be done in \SAP\Common by adding few configuration details.

I am not very clear still what i can do to achieve this. Any guidance will help.

Thanks,

Anjana