I suppose we all know that those who insist on using KDE 3.5 should stop upgrading and use YouCanToo's frozen repository
to install any applications. However I believe there's a way to upgrade a few selected applications or even install new ones.
1. Make a remaster and have it handy, just in case.
2. Select another repository of your choice and reload.
3. Click on the status tab to sort the packages according to their status. New packages should appear first, indicated by a star in a white box; then follow the upgradable packages indicated by a star in a brown box.
4. Go through the list of upgradable packages and see if there are any applications you'd like to update. When you find such an application right click on it and select "mark for upgrade". If the application doesn't bring any dependencies it should be fine to upgrade it; otherwise select cancel and don't
upgrade it! Modifying anything other than stand-alone applications, especially libraries, is likely to break some applications or even your installation.
5. Repeat the process for the new packages in case you'd like to install a recently added application. Apply the changes.
6. Before quitting Synaptic make sure you select the KDE 3 repository again and reload. You don't want to install anything from another repository by mistake.
7. Check that your updated applications work fine. In the unlikely event of broken applications, you can always force install the previous version from the KDE 3 repository.
This way I successfully upgraded PSPP and qDVDAuthor - but not
aMSN which required a number of dependencies.
I believe that as long as you upgrade only selected applications and not any dependencies you should be fine. However I can't guarantee there won't be any issues; perhaps a more experienced user should be able to clarify if this method is 100% safe.