If the flash is blank, the coprocessor can attach it, but will not be able to enter fast mode. You'll be able to read and write to it through the coprocessor, but it will be limited to single channel mode, and will not work from the graphics pipeline. You may need to consult the datasheet of your flash to double check whether the basic commands follow the same de facto standard.
Once you write the firmware blob onto the flash, switching to fast mode should just work. If the unified blob doesn't work, you may want to check with support if they can provide one specific for your model.