back up scritp

i want to be able to split the file into 659mb size so far i have after i have the script i want to be able to run it with crontab once a month or so

#!/usr/bin/bash

tar -cjvf /home/lance/backup/archive`date +%m%d%Y`.tar.bz2 /home/lance/bashscripts /home/lance/.avast /home/lance/.config/deluge /home/lance/.gnome2/nautilus-scripts

the archive will be stored in my backup folder in my home dir with the current date as part of the file name. the listing that follow after .bz2 are the folders or files i want backup. i found http://maketecheasier.com/how-to-compress-and-split-files-in-ubuntu/2008/10/06 it give dirttion on how to do split a single video file