Depends on the version of ID...
BUT, is this going to print? If it is, and its just a question of rotating the page view to make life easier, you can rotate the spread view in the Pages panel, or you can place and rotate the content to fit the current page. Your printer will appreciate that you didn't mix pages sizes orientations if you don't need to.
Yeah! Thanks that was a good hint.
I just rotated the content and the spread view and made a special master page for this format.