Disable Cleartype (text anti-aliasing) in IE9

Question

It's well documented (e.g. here) that IE9 ignores the OS-wide settings for font smoothing (aka anti-aliasing). Even if font-smoothing and ClearType are disabled in Windows, IE still shows anti-aliased fonts, which some users struggle to read, especially at small font sizes.

How can I disable all font anti-aliasing (ClearType or otherwise) in IE9?

More details:

Our company builds a web application which uses a lot of small fonts. With the release of IE9, some of our users have complained that IE9's default anti-aliasing makes our small fonts fuzzy or blurry. So we need to help our users who've installed IE9 and who want to turn off anti-aliasing.

Also, personally, I have trouble reading small, anti-aliased fonts, so I'd like a solution for my own use, even for sites I don't control.

In IE8 I could uncheck the "Always use ClearType for HTML" and then disable ClearType in the OS and IE8 would show all fonts aliased. But in IE9, this option is missing.

After some research about the problem, here's what I've learned: the core issue is that IE relies on DirectWrite for text rendering and does not support any of the newer rendering options which would draw text without anti-aliasing and respect the user's OS-wide default choices.

Making things worse, if you disable ClearType in the OS, in some cases IE will fall back to DirectWrite's default non-cleartype anti-aliasing which is even fuzzier than ClearType.