I've done this in a few installations. However, you may be disappointed if you are looking at this as a "zero footprint" solution. Using Arbortext Editor as an ActiveX control in a web page involves installing Arbortext (in at least a compact installation) as if it were any other browser plugin like Flash Player. But even the compact installation is pretty big, many MB of download and installation.
The upsides to using the ActiveX control include:
1) If you build a compact installation with the Deployment Kit, you can largely make the installation of Arbortext transparent. If you configure your web page embedding correctly, you can make the browser automatically download and install the Arbortext Editor code the first time a user accesses the page.
2) It makes it easy to integrate Arbortext Editor with web-based CMS and workflow management systems.
But by installing the Arbortext Editor code to run it in a web browser, you are essentially installing 90% of the full Arbortext Editor application. There's a description of what's left out of the ActiveX version of Editor in the Help Center, if you want to dig it up.