Hello,
Yes, it is possible to create a custom language generator. You can find more information in our
docs and we also have a
codelab about this topic.
Do note that in general you should not add your own features into the `Blockly` namespace. You can just call your generator `MyLang`; there is no need to call it `Blockly.MyLang`.
If you have additional questions please let us know! Thanks,
Maribeth