The CS2 download requires you to first get an Adobe account and a CS2 license, then download the installer from the CS2 downloads page. Therefore, while you can either virtualize the Server versions of OS X 10.6 (which is rather expensive and no longer available) or earlier, or hack virtualization software to allow installation of the OS X 10.6 client, the best option for current Mac users is to perhaps configure a Windows XP virtual machine and install the Windows version of CS2. The only versions of the OS X client that Apple supports in virtualization are those that do not include the Rosetta translator (OS X 10.7 and higher) which is required for running older PowerPC code on an Intel-based Mac.
Unfortunately for Mac users, CS2 is a PowerPC application, so it will require the use of either an Intel Mac running OS X 10.4 through 10.6 with the Rosetta translator installed, or the use of an older PowerPC Mac. Nevertheless, if you have an older computer or have virtual-machine software configured with an older operating system compatible with CS2, then you should be able to get CS2 running.
