We've successfully run Lucee and ACF9 on the same IIS installation. It
was Railo at the time, but here are my notes on how I got it working:
http://cfsimplicity.com/82/installing-railo-on-iis-alongside-coldfusion-9
Main thing I found was to *not* install the BonCode connector
automatically, but set it up manually for each Railo/Lucee site by
copying the BIN folder to the root folder and editing the handler
mappings in each site's web.config. That way you're not touching the
existing CF9 handlers in any way.
Julian