We are using VB.NET.
hm... you can control the direction of the whole page by changing the CSS file. So, what I am thinking now is you can add a CSS file that has RTL specification in the body element, and use a querystring to change which CSS file the software loads. The CSS is loaded dynamically by the software with a call to the sub OutputCSS. so, if you capture the querystring in this sub, you can change the CSS file to load for the page.
1) create a button that adds a query string (e.g. "RTL") to the current page
2) capture the querystring in the outputCSS function and change the CSS file to load based on the query string
3) remember the querystring in a session variable
4) outputCSS will check for the existence of the session variable, if it doesn't see the querystring.
Hope this is clear enough for you. however, it will change the direction of the whole page, so you have to take it into consideration and see whether it meets your need.