slapt-get --noupgrade kdelibs
There's a typo. It should be slapt-get --no-upgrade kdelibs
It didn't work. Nothing happened except a screen telling me various modifiers. Does slapt-get need some sort of package list beyond what GSlapt gets?
A symlink for libdvdread.so.3 didn't work, either. I continued to get a segmentation fault when I attempted to start K3B. I had a real mess on my hands.
There is no reason you shouldn't have a fully functional KDE 4.2 with the apps you want.
The thing is I never wanted KDE 4.2 to replace the KDE 3.x files that are installed in VL6. I just picked out some interesting-sounding KDE packages that were on the Deluxe CD2 and naively thought they'd install what they needed and wouldn't override what was already there. Ha! Instead I managed to break K3B, which I really like, and prevented Amarok from running.
I don't like KDE as my desktop, so all I'm interested in are some apps. Same for Gnome.
I did go through with renaming /usr to /usr_old and copying all of /usr from my other desktop that I'd never tried to put any KDE4 apps on. It wasn't extreme at all because by renaming /usr first, I risked nothing. If problems resulted, I could simply delete the /usr copied from the other computer and rename /usr_old back to /usr. I have plenty of drive space and the transfer was fast over Ethernet.
I'm happy to report that K3B started right up after I copied over the other /usr directory. I then installed Amarok 1.x from the repos and that's working, too.
There are a couple of directories in the old /usr_old/src that I need to copy into my /usr/src directory and I have to copy some entries from /var/log/packages on the other desktop into /var/log/packages on the formerly messed up computer.
I think I'll wait on KDE4.2 until I have a reason other than curiosity to install it. AND until it has a ready-for-prime-time K3B and Amarok.