The content translation support module supports Blossom dialogs out of the box as of version 2.0.2.
The content translation module exports translation files by traversing the content and using the dialogs in use at respective nodes to decide if certain fields should be included or not.
Because Blossom supports making decisions in your code on whether to include fields or not, for instance based on the node being edited, the user logged in and so on, it needs these things passed to it in order to create the dialog. This is called the dialog creation context.
Attached to this page are two custom classes that can be used with the content translation module to setup the needed context and this way add support for Blossom dialogs.
They're configured at /modules/content-translation-support/config/nodeDataToTranslateFinder. Choose class depending on whether you're using STK or not.