Sunbird: How to change the profile location?

Hi,
I'm using Sunbird Portable on a USB stick. I also have the same application installed on my desktop PC. I normally copy my profile from the USB stick to the desktop application in order to have a backup and (b) if for any reason I prefer to work from the desktop version.

However, I would prefer to have my profile kept on the D drive where only data are kept, as opposed to having it on the C drive which I try and limit to installed programs. Is there a setting in Sunbird portable to allow a different location for my profile when I run the portable application from my Desktop?