I know this is an old thread, but my comment might actualy help someone else.
I had issues with my manual installation of Solr on Windows, so I tried the Bitnami Stack. I have IIS running on port 80. Configured Bitnami's Apache Solr stack for 8982 (as Solr service will use port 8983). It's working flawlessly and I was able to migrate my existing Solr indexes easily.
So for anyone wondering if it's feasible, Ken's theory was right: it can be done and it's working fine on an IIS setup.