It seems like on Windows I have to uninstall Python before installing stackless (http://stackless.com/wiki/Download). I have Python 2.7 installed, a solution may be installing Stackless Python 3.2, but I will have to switch between Python 2 and 3 syntax. Is there anyway to install Stackless without uninstalling Python? Otherwise I'll loose all Python modules I've installed and the CPython interpreter.
There are binary snapshots which can be extracted over a standard Python installation, to turn it into a Stackless installation. This would keep all your modules. They are on the download page on the stackless web site.
However, the last time one of these was made, was for 2.7.2.
You could download the one for 2.7.2, look at what files are in it, download the Stackless installer for the standard Python version you are actually using and extract those same files, and put them into place manually.
Of course, if you really wanted an answer for this, you would ask on the Stackless mailing list.