It will not work.
It is, however, entirely true that AMD/ATI don't have any mechanisms in place to prevent it from working. The issue is that nVidia requires their partners to implement a BIOS lock-out that disables peer-to-peer PCIe writes on nVidia chipsets when non-nVidia cards are in the system. It can be, and has been, hacked... but sites that post instructions and/or hacked BIOSes tend to be taken down in short order. Besides, nVidia has historically been at the top of the performance heap more often than not (and, more importantly, SLI has historically outperformed CF), so most of the effort that has been put into this sort of thing has gone towards making SLI run on non-nVidia boards (which is another single-sided nVidia-introduced incompatibility).
Now Diamond was talking about enabling CF to run on any chipset with Diamond graphics cards late last year... but there is exactly zero mention of it anywhere other than the initial press releases. Google "Diamond xDNA" and you'll get a handful of hits, all dating from the initial announcement. It could be worth e-mailing Diamond tech support and asking if they actually implemented this feature, or if the were *cough* "convinced" to silently drop the entire project.