Using ValidateRequest

[aualias]

I have a TextBox that the user can enter html code into. I cannot send the
entered text to the server without setting ValidateRequest to false.

Is there a way that I can HtmlEncode() on the fly, so that the user can
enter html into the text box and the encoded text gets posted to the server?
( without changing the text in the control, I cannot see how this can be
done )

Or... Can I turn off ValidateRequest for only that one control?

Thanks.

David