No, you can't change the path in Atrract-Mode. You could use symbolic links to point the scraper to your desired folders though
for example
/home/pi/.attract/scraper/snes --> /home/pi/RetroPie/roms/snes/snap
something like
sudo ln -s -d /home/pi/RetroPie/roms/snes /home/pi/.attract/scraper/snes