Response file help (win2003 winxp bootable CDs)

Hi admins, I'm trying to figure out how to change the Regional setting "Location" in the response file on the win2003 cd (unattend.txt or winnt.sif). As far as my research goes, there is no entry available to change that setting directly into the response file. So, I tried a few tricks by switching the registry value with this:

[GuiRunOnce] Command0="reg add HKEY_CURRENT_USER\Control Panel\International\Geo /v Nation /t REG_SZ /d 39 /f" 

but there's a space between Control and Panel and I can figure out a way to put quotes inside quotes so the script executes it correctly. I'm maybe wrong in this, it's the first time I'm using the [GuiRunOnce] container. Any ideas are welcome. Thanks for your help!