I'm afraid I can't help, but it seems like it'd be pretty straightforward to do. Maybe just create your own bare Blockly project outside the IDE and get it working as you want (the Blockly forums could help you with that) and then when it's going try and get it into the Web IDE - but I don't think you'll have any big problems.
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
I'm afraid I can't help, but it seems like it'd be pretty straightforward to do. Maybe just create your own bare Blockly project outside the IDE and get it working as you want (the Blockly forums could help you with that) and then when it's going try and get it into the Web IDE - but I don't think you'll have any big problems.