Yes, I know it's not an IMGBurn feature, that's why I posted in the "Suggestions" area. If it's already been posted somewhere else, I was not able to find it -- and I did spend quite a bit of time looking before posting.
The only thing similar I've seen was where someone was asking for something that would split up a directory of files onto separate disks -- I'm not trying to do that.
It just seems that, given that IMGBurn already has the machinery for doing this as part of the "queue", that it'd not be too difficult to support.