For example, using the root discussed in the article:
1. Download the root cert from http://ctldl.windowsupdate.com/msdownload/update/v3/static/t... (or save it from the browser's certificate viewer)
2. Open certmgr and import it into 'Untrusted Certificates'.
(This just adds it for the current user's store. Could also import into the computer store by running mmc, adding the Certificates snap-in, and specifying 'Computer account' as the target.)
3. Restart browser. Go to https://certplusrootcag1-test.opentrust.com/ - it should say the certificate is revoked.
This only works for browsers like IE and Chrome, that use the Windows certificate store. Firefox has its own so would have to be done separately.