IMPORTANT: First, make sure you have restored your partitions to their original state! I also had Nemo installed on a partition between MyDocs (sdX1), and harmattan rootfs (sdX2). I recreated the MyDocs partition with gparted, but the update still bricked my phone. Did you touch the rootfs or the home partition? Make sure that your MyDocs partition starts at sector 1024. My problem was caused because gparted always creates partitions starting from 2048. After I recreated it with parted, flashing went fine.
AFAIK the MyDocs partition of a 64GB should start at 1024 and end at 112672767, otherwise flashing WILL fail. If this is not what you have, you have to recreate the partition using command-line parted -- let me know and I'll provide you with specific instructions.

IIRC, you need to provice both the firmware image and the EMMC image to the flasher utility. Look at the first post in this thread:
http://talk.maemo.org/showthread.php?t=81579