Inject HTML in content blocks

Hello,

We would like to simulate a function in Sitefinity that updates html in Content Blocks before publishing. Sitefinity already does that with certain html objects like images, videos and documents where they are assotiated with an sfref attribute that is then used by some internal component to update the url in case it has been changed.

We have a need to do something similar where we need to check/update the URLs of certain silverlight and flash controls in case a change has occured, so we would reference that by some unique identifier as the sfref attribute but then how do we add our implementation into the pipeline to make sure that the html never breaks?

Thanks
Amr