Well I completed my swap for my Legendary last night. I then asked could we also do this for my console as well. Truth be told the rep kinda freaked out thinking he had swapped a console code instead of a Legendary Edition. I assured him I have both and was just asking. He then double checked my code from Legendary ( pretty sure to check if I had given him a Legendary code instead of a console) and said that no, they will NOT swap codes from the console for a disc.
This being said, you could always try it and see what happens, because it seems they are not checking the codes right off. So I would day proceed with caution if you try to do this. I then was told I would receive my DLC codes and to use them ONLY AFTER I had the disc copy. I was told 3-5 days shipping and given an order number and about 5 seconds later my DLC codes in my email. So looks like this is working pretty well so far. But again you can TRY on the console but no guarantees as they stated it was not eligible.