Question: can I upload files using `selenium RC` in IE?

Answer: 
The short answer is that in general [you can't](http://wiki.openqa.org/display/SEL/Selenium+Core+FAQ#SeleniumCoreFAQ-Ican%27tseemtouseSeleniumCoretouploadafile%3BwhenItrytotypeinthefileuploadtextfield%2Cnothinghappens!), due to browser security restrictions. Think about it, if Javascript code could programmatically upload a file to the server, it could send sensitive files to the server without the user ever noticing.

There are ways to work around it, as Niraj notes, but they involve using another tool to inject keypresses into the window system event queues. Also, you can run using the \*chrome backend which is \*firefox with lower security barriers.
In firefox and other browsers you can upload a file just using type command of selenium. 

See here <http://aboutselenium.blogspot.com/2011/02/handling-file-upload-using-selenium.html>