[wlug] Splitting an image file over CR ROMs

Hello, I have a disk image of about 8.4G that I took from a friends computer about 18 months ago. Since then the harddrive has been reformatted and that data lost. I would like to send disk image via CD's to the UK where the disk image can be reassembled. I imagine that might take about 12-13 CD's the file is recognised as a xxxxxx.dat file and I am sure I made it using something like dd if=/dev/hda5 of=/mnt/hdb11/image_name.dat Would people be prepared to offer any hints on how to do that? Cheers