Easy is relative, but I would definitly say no, because this is not the way how Blockly is thought to works. Blockly is designed to make consistent blocks which are interpretated after through Generators. This is because manipulating Strings is a lot more easier than complex DOM Objects.
But there will be definitly a possible solution, which will cost a lot of effort. There are no limits set by Blockly Developers, but overwriting functions which works on a deep layer usually brings more problems at programming. But mostly of the things you will needed are documented.