Geez you can get the packages easily for sid. Even kde has the packages hosted and did from the moment kde 3.0.3 came out and kde 3.0.1-3.0.2 has been available for a while now and the locations have been publicized in a number of locations. Just add the apt lines and install it. I have been running kde 3.0.x in debian sid for a while now without any problems.