Rar files probably won't work because they have headers even if you don't use compression.
This post has some information on split file requirements and a Linux command to do it:
http://reboot.pro/17128/#entry160105Under Windows you could use something like
HJSplit -- I've never tried this app, but it looks like it should work.
Also later today when the isostick website launches, I will also release the ISO Manager software for Windows. It's still in testing so it
will have bugs, but the basics will work!
It automatically detects your isostick and lists any iso files on it. You can drag isos (or whole folders of isos!) onto it, and it will automatically split any large isos -- it also lists split isos just once, for simplicity.
Then you can just double-click an iso in the list, and it will be inserted into the optical drive.
Hope that helps!