Wireshark · Ethereal-users: [Ethereal-users] Slice a big file into small chunks,

[Steve Abrahall <sa@xxxxxxxxxxxxxxxx>]

Not quite sure if this is what your after but it may be worth having a 
look at
If your comfortable with working with unix type operating systems and 
shell scripting

This is a script I wrote for osX it could be moded for other unix 
platforms


http://wiki.ethereal.com/osXextraction

HTH

Steve