Regarding the dd comand to dump the BR. You must split the file when dumping it.
on this example the file will be dumped on files of 1Gb you can create a bath file or execute one by one
example of bath file
Code:
#############
#!/bin/sh
#
/bin/dd if=/dev/cdrom of=cd00 bs=1024 count=1000000 skip=0000000
/bin/dd if=/dev/cdrom of=cd01 bs=1024 count=1000000 skip=1000000
/bin/dd if=/dev/cdrom of=cd02 bs=1024 count=1000000 skip=2000000
/bin/dd if=/dev/cdrom of=cd03 bs=1024 count=1000000 skip=3000000
/bin/dd if=/dev/cdrom of=cd04 bs=1024 count=1000000 skip=4000000
/bin/dd if=/dev/cdrom of=cd05 bs=1024 count=1000000 skip=5000000
/bin/dd if=/dev/cdrom of=cd06 bs=1024 count=1000000 skip=6000000
/bin/dd if=/dev/cdrom of=cd07 bs=1024 count=1000000 skip=7000000
/bin/dd if=/dev/cdrom of=cd08 bs=1024 count=1000000 skip=8000000
######################
this will create 9 files from cd00 to cd08 on the actual folder
if = imput file so /dev/cdrom is not needed to be mounted
of= output file
bs= size od block
count = number of block to dump
skip= number of block to skip
if you are dumping a file from 5 Gb no problem the files cd06 cd07 cd08 will be 0 size
in order to joing it all the files you need to have another file system that support bigest files.
for example to joint it on windows you can use the command copy /b
regards
Spirax