Would it not be easier to just move a few mount points to the storage card? For example, mount /usr as /media/mmc2/usr and /home as /media/mmc2/home? I believe this could be done in /etc/fstab but I haven't tried it. I simply moved all my files to the MMC and also moved maemo mapper map files to the mmc. I also noticed that the rss reader takes up a LOT of disk space so I cleaned that out.