Looks like divs will not go outside of their body's width. Even within another div.
I threw this up to test (without a doctype though) and it does not work as thought.
.slideContainer {_x000D_
overflow-x: scroll;_x000D_
}_x000D_
.slide {_x000D_
float: left;_x000D_
}
_x000D_
<div class="slideContainer">_x000D_
<div class="slide" style="background: #f00">Some content Some content Some content Some content Some content Some content</div>_x000D_
<div class="slide" style="background: #ff0">More content More content More content More content More content More content</div>_x000D_
<div class="slide" style="background: #f0f">Even More content! Even More content! Even More content!</div>_x000D_
</div>
_x000D_
What i am thinking is that the inner div's could be loaded through an iFrame, since that is another page and its content could be very wide.