you should use the block module to create a block HTML dynamicly and set itd ID to a page stored in the HTML module. But I had no time to finish that module properly. So tell me where it blocks and if you have time you can work on it (it's not hard and I am having tough work with the forum development)
I had done that trick to put images within a block, but I don't know how to include html, or Is that the part you said you haven't finished? If you tell me what's missing I'll be happy to work on it.
You have to create HTML content with the HTML module : index.html?module=html
Then with the block module index.html?module=block you can create dynamicly an HTML block with an ID property equals to the ID of you content you want to see in the block.
But the block module is still caca. The main fx are there, but the block creation and management is not finished. So you can have a look at the block module : nukes/nukes/src/main/org/jboss/nukes/core/modules/block/BlockModule.java
and help there