Option 1: Download VL packages via either vlapt or ftp site. Check out this VL forum thread for details:
http://vectorlinux.com/forum/viewtopic.php?t=6292
Option 2: Download the packages from linuxpackages.net. Be warned though, although VL is based upon Slackware I'm not 100% sure that the linux packages are compatible with VL.
Option 3: Download the KDE source and compile it yourself. (This is going to take a while if you chose this option).
HTH and Good luck