This is a problem I've been dealing with since since starting the "Limekiller at Large" series. Since it's a hybrid between a serialized novel and a comic book, it's essential that I not only get images in, but that they be where I put them.
I work in Open Office, so one thing I do is use either the Anchor to page, or anchor to paragrah commands. I also export as a pdf, and I use calibre to do my own conversions.
Not one hundred percent successful yet, but still working on it.