From a quick Google search, it seems like everyone else on the Internet has the same problem with Macs and DDS files in PS. xD
It seems like no one has come to a real conclusion other than workarounds (like converting, editing, and converting back). I think your likely solution would be to create a Windows environment on your Mac, be it through Wine or a virtual machine or even dual-booting operating systems. Or you can learn to like Gimp.
I'm sorry I don't have more to offer (as a Windows user), and it sucks that Macs are so prohibitive in this case. Hopefully something will appear to you. Good luck on your quest!