The last time I built an executable with an installer, it broke it up into multiple installer files, each one suitable for storage on a 1.4M floppy.
In any case, one thing you could do is put the installer files in a Zip archive and then have the zip program you're using split the archive into smaller files that you can later rejoin. I just checked and WinZip 8.1 will generate split segments as small as 64K.
Mike...