why? kde-3.1 and kde-3.2 are sloted, and unslotted qt-3 makes trouble with it - kde-3.1 totally looses its style support with qt-3.2 or newer - kde-3.2 on the other hand cannot work without qt-3.2 or greater ...and since kde-3.1 and kde-3.2 exist in different slots, it's very likely that because of this at least one of these kde won't work along with the other if there's no slot to separate one qt version from the other
It's an interesting idea. Note that there really is no problem using qt 3.3 with any older versions of KDE. The style support that was lost is due to build string differences, and can be fixed by re-emerging any old kdelibs you have lying around.
Going to set this as a wontfix, as the current system works fine and qt 4 will be out very soon anyway.