Killing the user session on the Unix server is as simple as killing the PPID. If you list all logged in uses with `who -T` you will see the process ID you need to kill (column 8). Then just do a 'kill -9 process_ID'. If you want to automate this to kill all telnetted users you can use a short script -
for PID in `ps -ef|grep "in.telnetd"|awk '{print $2}'
do
kill -9 $PID
done
All users that telnet into the box will have an in.telnetd process.
If you want to login as admin via telnet to w2k I'm not sure - but for Solaris edit /etc/default/login and comment out the line that reads CONSOLE=/dev/console. If this line is present it means root can only log in at the console; otherwise root can login from anywhere.
I hope this helps. Good luck.