I don't think it can be done using just CSS (although I would be happy to be proved wrong).
There is quite a good discussion of the subject here: http://stackoverflow.com/questions/5123417/css3-how-do-i-position-a-left-scrollbar-on-a-tbody-element-of-a-table-for-google
What would work though, is using a jQuery plugin such as Tiny Scrollbar: http://baijs.nl/tinyscrollbar/
You can use this, then apply a style of "float:left" to the scroll bar and have it appear on the left hand side of the div.
Here's a working example: http://jsfiddle.net/MsAgZ/
Of course, this would provide a good deal of usability problems, so just because it is possible, doesn't make it a good idea.