Here are some linux commands that can be used to split and combine .ISO file.
Goto the directory in which .iso file is located
bond@bonds-desktop:~$ cd Downloads
to split file "myFile.iso" in parts of size 3gb
bond@bonds-desktop:~/Downloads$ tar cvzf - myFile.iso | split -d -b 3000m - myFile.iso.tar.gz.
output shown- myFile.iso
This creates parts as follows in the same folder
myFile.iso.tar.gz.00
myFile.iso.tar.gz.01
Now to combine parts
bond@bonds-desktop:~/Downloads$ cat myFile.iso.tar.gz.* | tar xvzf -
output shown- myFile.iso
and file is recreated
commands used are (you can split size to any size you want , here 100m)
tar cvzf - filename.iso | split -d -b 100m - filename.iso.tar.gz.
cat myFile.iso.tar.gz.* | tar xvzf -