Currently you can only 'import' HTML data in the UI (using uidoc.import). I often generate HTML, that I want to put into Rich Text fields. It allows for a lot more flexibility than using the standard RT methods.
It's not pure html, but dxl is used for exactly this. As you say you're generating the html, why not just generate dxl and import that - it's not vastly different, and gives you all the control over the styles that you need. Dan
I agree this should be a native method. In the meantime, for what it's worth, our Midas Rich Text LSX does allow you to import HTML into rich text, and with a great deal more fidelity and control than the native method. It is completely backend, using our own engine, so you can do it from a servre, scheduled agent, or whatever. See { Link }