The sums work out at a maximum total bitrate of 1300-1400kbps. The easiest approach is probably to encode the entire length to an AVI, with MP3 audio at 192kbps and Xvid video, all quality options enabled, at 1100kbps (which is more than enough for video at 320x240). Then use something like Nandub or AVI-Mux GUI to conveniently split the AVI into 100MB chunks.