Have you tried Photoshop Elements? I'd imagine that it would have very similar capabilities.
As for CS2, well, I'd tend to be leery of trying to pick up a second-hand package via the Internet, due to the strong possibility of paying for a package that someone may not be using, but they may have updated, using the serial #, which means that what they pass off to you would not be legit.
Another alternative is to shoot in Raw, and use the Canon Raw software Digital Photo Professional (DPP) to set the Picture Style to Monochrome and then play with the various settings. Raw gives you the freedom to play around with such things, and DPP has the convenience of starting with your in-camera settings, but with Raw allowing you to switch things around freely.
Of course if you are shooting Raw other Raw processors give you that ability as well, since a B&W/Monochrome shot is simply the Raw data, the same as has been used for a full RGB color jpeg, but the data has been processed to desaturate color tones and then to apply whatever "effects"/tones you wish (e.g. Sepia).