If you've installed Vector Linux you already have a multi-user system. If you want people to login remotely you have any of a number of ways to do this. Are they going to be logging in from other Linux systems, from Windows, from Mac OS X, or
Do you prefer they use the command line or a GUI? Is it OK to login at the command line and then start the GUI?
The answers will vary depending on the answers to the above questions.
My preference would be for you to use SSH and to permit X forwarding so that the remote users can have a GUI session. This would entail nothing more than starting the sshd service for your chosen runlevel in vasm. On the remote side a Linux/UNIX user has all they need if openssh is installed and it is by default on most systems. A Windows user would need to install a GUI ssh client. I like Putty, personally, because it is free and pretty easy to use.
Most commercial clients I have use either ssh or XDCMP (logging directly into X) and use commerical (read: expensive) Windows clients like Hummingbird Exceed or Reflection X.