It seems that applying the unicode-bidi with the direction property in an input tag doesn't work in IE8. Here is a sample: (the unicode-bidi works fine for a div element but doesn't work for the value set in the input tag - note that it is working in firefox).
<html>
<body>
<div style="direction:ltr;unicode-bidi:bidi-override;">ח"ש<div>
<input type="text" name="TextBox" style="direction:ltr;unicode-bidi:bidi-override;" value="ח"ש"></input>
</body>
</html>