I use the "hard way" to convert Aperture books to MyPublisher. Books are the same dimensions (MyPubliser actually prints Aperture books, albeit with different everything). Simply make your book in Aperture – this way you have a PDF that can be optimized for iPad, can test print at home, etc. Then transfer everything over using the same images, text, everything. Text holds format using copy/paste. Images are a little bit of a problem – where you need borders you will have to add them first. And sizing is a nightmare – Aperture gives you the sizes, then you have to use a ruler on your display to set the picture box sizes in MyPublisher before placing.
You will notice a couple of differences: Apple books are best viewed in bright interior light. MyPublisher books seem to want to not wash out in direct sun – I think they are too dark. I like to bulk-set the Aperture images 1/4 to 1/2 stop lighter when using them in MyPublisher, scenics especially are simply too dark otherwise.
In MyPublisher, be sure to wait for a half price special.