I've seen videos on YouTube about this, and don't know of any for-certain reason it wouldn't work. The only concern I'd have is whether the pH of the two separate solutions comes out right. Bleach (modern type with EDTA/PDTA) should be a little acidic, to ensure any developer that gets into it is inactive (active developer in bleach can lead to strong color formation). C-41 fixer is normally mildly alkaline, unlike most B&W fixers which are acidic. The blix, mixed according to instructions, obviously can't be both; my guess would be that the fixer is allowed to be acidic rather than trying to keep the blix alkaline (and risk magenta film).