Convert cross-CHM links to web help links while keeping cross-CHM functionality

Hi. I'm working with a help system that consists of 28 merged CHM files. There are many topics that have links to topics in other CHM files. The issue is that we now want to publish the help online -- but we want to keep the CHM files too.

For new links, I think I would approach this by creating two links, one for the CHM output and one for the web output, and use conditional tags to control which appears in the output.

My problem is what to do with the hundreds of existing links. I don't have the bandwidth to manually change all of them. So I need an automated way to update the links.

My original post had a code sample with a link that landed me in the moderator queue. I'll replace it with an image showing what I hope to accomplish...

Has anyone tackled this type of situation? Any suggestions would be greatly appreciated.

Ashley