Forum Moderators: not2easy
To add it, you can use javascript, e.g. IE8.js [code.google.com] will add the support you seek in IE6 and IE7.
Do take care with that script: it'll add support for lots of other things as well, so you might need to revisit more of your IE workarounds.
Alternatively a degraded solution for the obsolete browsers can also be considered. There's no rule that says the decade old browsers must render out sites exactly the same as the modern ones, is there?