Want to test KDE 3.5b2 - how to revert to KDE 3.43 later?

The subject says it all I guess. I want to test KDE 3.5b2, but if I have a problem I would like to return to KDE 3.43. I know that YaST detects the prescence of newer versions of packages and hence I can use "Update all in this list when a new version is available" but I am not sure this will work in the reverse direction - tell me when an *older* version is available. Can anyone give me a set of instructions to "safely" test 3.5b2? Thanks. Shriramana.